Why are void[] contents marked as having pointers?

[Vladimir Panteleev]

On Tue, 02 Jun 2009 01:01:00 +0300, Christopher Wright <dhasenan at gmail.com> wrote:

> Vladimir Panteleev wrote:
>> On Mon, 01 Jun 2009 14:10:57 +0300, Christopher Wright  
>> <dhasenan at gmail.com> wrote:
>>
>>> Vladimir Panteleev wrote:
>>>> On Mon, 01 Jun 2009 05:28:39 +0300, Christopher Wright   
>>>> <dhasenan at gmail.com> wrote:
>>>>
>>>>> Vladimir Panteleev wrote:
>>>>>> std.boxer is actually a valid counter-example for my post.
>>>>>> The specific fix is simple: replace the void[] with void*[].
>>>>>> The generic "fix" is just to add a line to    
>>>>>> http://www.digitalmars.com/d/garbage.html adding that hiding your   
>>>>>> only  reference in a void[] results in undefined behavior. I don't   
>>>>>> think this  should be an inconvenience to any projects?
>>>>> What do you use for "may contain unaligned pointers"?
>>>>  Sorry, what do you mean? I don't understand why such a type is  
>>>> needed?  Implementing support for scanning memory ranges for  
>>>> unaligned pointers  will slow down the GC even more.
>>> Because you can have a struct with align(1) that contains pointers.  
>>> Then  these pointers can be unaligned. Then an array of those structs  
>>> cast to  a void*[] would contain pointers, but as an optimization, the  
>>> GC would  consider the pointers in this array aligned because you tell  
>>> it they are.
>>  The GC will not "see" unaligned pointers, regardless if they're in a  
>> struct or void[] array. The GC doesn't know the type of the data it's  
>> scanning - it just knows if it might contain pointers or it definitely  
>> doesn't contain pointers.
>
> Okay, so currently the GC doesn't do anything interesting with its type  
> information. You're suggesting that that be enforced and codified.

I wasn't suggesting any GC modifications, I was just suggesting that void[]'s TypeInfo "has pointers" flag be set to false.

-- 
Best regards,
 Vladimir                          mailto:thecybershadow at gmail.com