Thread overview
Best way to confine project to 64 bit builds only?
Oct 17
NonNull
Oct 17
Basile B.
Oct 17
NonNull
Oct 17
NonNull
Oct 17
Dennis
Oct 17
NonNull
October 17
I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same, and I have translated it into very similar D just like https://dlang.org/blog/2018/06/11/dasbetterc-converting-make-c-to-d/

D has the size of long fixed at 64 bits, so a pointer now has to be 64 bits. So I want to put something into the source to ensure an attempt to make a 32 bit build fails. What is the best way to do this?
October 17
On Saturday, 17 October 2020 at 14:50:47 UTC, NonNull wrote:
> I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same, and I have translated it into very similar D just like https://dlang.org/blog/2018/06/11/dasbetterc-converting-make-c-to-d/
>
> D has the size of long fixed at 64 bits, so a pointer now has to be 64 bits.

No it's wrong. A pointer always has the size of a general purpose register.

> So I want to put something into the source to ensure an attempt to make a 32 bit build fails. What is the best way to do this?

anyway you have several options:

---
version(X86)
    static assert (false, "not for i386");
---

or

---
static assert (size_t.sizeof != 4, "blablalala");
---
October 17
On Saturday, 17 October 2020 at 14:50:47 UTC, NonNull wrote:
> I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same

static assert(long.sizeof == void*.sizeof);
October 17
On Saturday, 17 October 2020 at 14:56:33 UTC, Basile B. wrote:
> On Saturday, 17 October 2020 at 14:50:47 UTC, NonNull wrote:
>> I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same, and I have translated it into very similar D just like https://dlang.org/blog/2018/06/11/dasbetterc-converting-make-c-to-d/
>>
>> D has the size of long fixed at 64 bits, so a pointer now has to be 64 bits.
>
> No it's wrong. A pointer always has the size of a general purpose register.

You misunderstand. The original C only works if the size of a pointer is the same as the size of a long. So when translated into D in a simple way where the size of a long is always 64 bits the D will only work if the size of a pointer is 64 bits.
October 17
On Saturday, 17 October 2020 at 14:50:47 UTC, NonNull wrote:
> I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same, and I have translated it into very similar D just like https://dlang.org/blog/2018/06/11/dasbetterc-converting-make-c-to-d/
>
> D has the size of long fixed at 64 bits, so a pointer now has to be 64 bits.

If you want to exactly match the original C code's semantics, I suggest translating (unsigned) long with c_long or c_ulong. You can import them here:
```
import core.stdc.config: c_long, c_ulong;
```

Then you could add this:
```
static assert(c_long.sizeof == size_t.sizeof);
```

This will fail on Windows 64 bit, where C longs are 32-bit and pointers 64-bit.
October 17
On Saturday, 17 October 2020 at 14:56:35 UTC, Adam D. Ruppe wrote:
> On Saturday, 17 October 2020 at 14:50:47 UTC, NonNull wrote:
>> I have inherited an open source C project that assumes that the size of a long and the size of a pointer are the same
>
> static assert(long.sizeof == void*.sizeof);

That's a nice clean answer!
October 17
On Saturday, 17 October 2020 at 15:03:29 UTC, Dennis wrote:
> If you want to exactly match the original C code's semantics, I suggest translating (unsigned) long with c_long or c_ulong. You can import them here:
> ```
> import core.stdc.config: c_long, c_ulong;
> ```
>
> Then you could add this:
> ```
> static assert(c_long.sizeof == size_t.sizeof);
> ```
>
> This will fail on Windows 64 bit, where C longs are 32-bit and pointers 64-bit.

That is useful information in general, I did not know about core.stdc.config and it is useful in future projects!

But for my project the C works at 64 bits except on Windows for the reason you gave. So by translating long in C to long in D it loses 32 bits but gains 64 bits on Windows. This is what I want.