manual memory management

[deadalnix]

On Thursday, 10 January 2013 at 01:10:06 UTC, H. S. Teoh wrote:
> On Thu, Jan 10, 2013 at 01:50:28AM +0100, Adam D. Ruppe wrote:
>> On Thursday, 10 January 2013 at 00:18:26 UTC, Walter Bright 
>> wrote:
>> >And that is not dereferencing null, it is dereferencing 
>> >0x1000000.
>> 
>> Yes, but it is worth noting that dmd will happily compile that 
>> code,
>> even if marked @safe - just because the pointer on the language
>> level is null doesn't mean it is memory safe at the assembly 
>> level.
>> 
>> the generated code with @safe is still just what we'd expect 
>> too:
>>    3:   31 c0                   xor    eax,eax
>>    5:   c7 80 00 00 10 00 0a    mov    DWORD PTR 
>> [eax+0x100000],0xa
>
> Yeah that's exactly what I was thinking too. To DMD, it's a 
> null pointer
> dereference. But actually, it's dereferencing something else, 
> because
> x.fieldName is, in general, *not* null when x is null.
>
> Hmm. This looks like another hole in SafeD? Unless null pointer 
> checks
> are inserted. (The checks have to be made on x, not 
> x.fieldName, of
> course.)
>

That is exactly why my NPE proposal do trigger on other address 
that 0. Still, it require to add check for big objects (or high 
indices in arrays).