Re: Cast a struct to void*
On Friday, 9 January 2015 at 19:03:04 UTC, Steven Schveighoffer
wrote:
On 1/9/15 1:50 PM, John Colvin wrote:
On Friday, 9 January 2015 at 18:35:56 UTC, anonymous wrote:
On Friday, 9 January 2015 at 18:25:42 UTC, John Colvin wrote:
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of
type S to
type void*
This is actually a compiler bug!
So it is! The same happens with e.g. casting void* to string.
Annoyingly it passes __traits(compiles, ...)
Cast a struct to void*
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of type S
to type void*
}
Is there are a good reason for this being disallowed?
Re: Cast a struct to void*
On Friday, 9 January 2015 at 18:25:42 UTC, John Colvin wrote:
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of type
S to type void*
}
Is there are a good reason for this being disallowed?
You'd expect `cast(void*)s == s.p`? That doesn't work for any
type of p. You can do it with a slightly fancier (and more
dangerous) cast: `*cast(void**)s`.
Re: Cast a struct to void*
On 01/09/2015 10:25 AM, John Colvin wrote:
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of type S to
type void*
}
Is there are a good reason for this being disallowed?
I know two options:
a)
alias p this;
b)
auto opCast(T : void*)()
{
return p;
}
Ali
Re: Cast a struct to void*
On Friday, 9 January 2015 at 18:35:56 UTC, anonymous wrote:
On Friday, 9 January 2015 at 18:25:42 UTC, John Colvin wrote:
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of type
S to type void*
}
Is there are a good reason for this being disallowed?
You'd expect `cast(void*)s == s.p`? That doesn't work for any
type of p.
I was expecting it to work regardless of the type of p. I have an
8 byte (on x86_64) struct which I want to reinterpret as a void*
You can do it with a slightly fancier (and more dangerous)
cast: `*cast(void**)s`.
Yuk. Better than nothing though. Thanks :)
Re: Cast a struct to void*
On 1/9/15 1:50 PM, John Colvin wrote:
On Friday, 9 January 2015 at 18:35:56 UTC, anonymous wrote:
On Friday, 9 January 2015 at 18:25:42 UTC, John Colvin wrote:
struct S
{
void* p;
}
void main()
{
S s;
auto a = cast(void*)s; //Error: e2ir: cannot cast s of type S to
type void*
This is actually a compiler bug! I will check to make sure it's not
already filed, and file if it's not. However, I don't think the code
should work, it just shouldn't print e2ir.
}
Is there are a good reason for this being disallowed?
You'd expect `cast(void*)s == s.p`? That doesn't work for any type of p.
I was expecting it to work regardless of the type of p. I have an 8 byte
(on x86_64) struct which I want to reinterpret as a void*
You can do it with a slightly fancier (and more dangerous) cast:
`*cast(void**)s`.
Yuk. Better than nothing though. Thanks :)
This is what reinterpret_cast from C++ does.
-Steve
