[SLOF] [PATCH] instance: Fix set-my-args for empty arguments

[Thomas Huth]

On 08.06.2016 18:36, Segher Boessenkool wrote:
> On Wed, Jun 08, 2016 at 06:02:54PM +0200, Thomas Huth wrote:
>>> diff --git a/slof/fs/instance.fs b/slof/fs/instance.fs
>>> index 9e5c921..225a2bf 100644
>>> --- a/slof/fs/instance.fs
>>> +++ b/slof/fs/instance.fs
>>> @@ -134,7 +134,7 @@ CONSTANT <instancevariable>
>>>        2dup my-self instance>args 2!   \ | write into instance struct  ( old-addr len new-addr )
>>>        swap move                       \ | and copy the args           ( )
>>>     ELSE                               \ ELSE                          ( old-addr len )
>>> -      my-self instance>args 2!        \ | set new args to zero, too   ( )
>>> +      swap my-self instance>args 2!   \ | set new args to zero, too   ( )
>>>     THEN                               \ FI
>>>  ;
>>
>> You're right, the old code stored the address and length in the wrong
>> order into instance>args and instance>args-len. However, the code likely
>> simply expected to write zeros to both fields instead, so maybe it is
>> better to do this instead:
>>
>> 	nip 0 my-self instance>args 2!
>>
>> ... that way you'd make sure that instance>args never contains a bogus
>> pointer if instance>args-len is 0.
> 
> Why treat a length of zero special at all?  alloc-mem already knows how
> to handle it (it returns 0 for the address).

You're right - it should work without the IF-statement, too!

 Thomas