manual memory management

[H. S. Teoh]

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.)


T

-- 
Notwithstanding the eloquent discontent that you have just respectfully
expressed at length against my verbal capabilities, I am afraid that I
must unfortunately bring it to your attention that I am, in fact, NOT
verbose.