• MyNameHere (14/14) Aug 19 2022 I am receiving this error:
• kinke (3/3) Aug 19 2022 It's a method returning a `CHAR*` - `_DevicePath` is the actual
• MyNameHere (3/3) Aug 19 2022 Thank you, that seems to have resolved the issue, though I wish
• Steven Schveighoffer (5/8) Aug 19 2022 Most likely that "member" is a macro in C. D doesn't have macros, so it
• kinke (8/14) Aug 19 2022 Nope, it's really a dynamically sized struct with a last
• kinke (5/8) Aug 19 2022 Oh and `DevicePath()` is a convenience member returning a pointer
• MyNameHere (2/6) Aug 19 2022 I am using ```-BetterC```, so that path is closed to me, I think.
• Steven Schveighoffer (3/9) Aug 19 2022 dynamic arrays are really slices, and they are allowed in betterC.
• Tejas (3/10) Aug 19 2022 I believe you aren't allowed to _append_ to dynamic

MyNameHere <MyNameHere example.com> writes:

I am receiving this error:

```
Error: no property `offsetof` for type `char*`
```

from this snippet:

```d
import core.sys.windows.setupapi;

void main() {
     SP_DEVICE_INTERFACE_DETAIL_DATA_A DeviceInterfaceDetail;
     uint Offset = DeviceInterfaceDetail.DevicePath.offsetof;
}
```

You may try this at https://run.dlang.io/, build with ```LDC```, 
with argument: ```-mtriple=x86_64-windows-msvc```.

kinke <noone nowhere.com> writes:

It's a method returning a `CHAR*` - `_DevicePath` is the actual 
member. I guess it's a dynamically sized struct, which cannot be 
mapped directly to D, hence this representation.

MyNameHere <MyNameHere example.com> writes:

Thank you, that seems to have resolved the issue, though I wish 
these sorts of problems would stop cropping up, they are souring 
the experience with the language.

Steven Schveighoffer <schveiguy gmail.com> writes:

On 8/19/22 9:49 AM, MyNameHere wrote:
 Thank you, that seems to have resolved the issue, though I wish these 
 sorts of problems would stop cropping up, they are souring the 
 experience with the language.

Most likely that "member" is a macro in C. D doesn't have macros, so it 
uses properties.

The error message could be better though.

-Steve

kinke <noone nowhere.com> writes:

On Friday, 19 August 2022 at 14:22:04 UTC, Steven Schveighoffer 
wrote:
 On 8/19/22 9:49 AM, MyNameHere wrote:
 Thank you, that seems to have resolved the issue, though I 
 wish these sorts of problems would stop cropping up, they are 
 souring the experience with the language.

 Most likely that "member" is a macro in C. D doesn't have 
 macros, so it uses properties.

Nope, it's really a dynamically sized struct with a last 
`CHAR[1]` member: 
https://docs.microsoft.com/en-us/windows/win32/api/setupapi/ns-setupapi-sp_device_interface_detail_data_a

Just like with C, these abominations need very special care, and 
regularly allocating on the stack or using as an aggregate field 
isn't possible.

kinke <noone nowhere.com> writes:

On Friday, 19 August 2022 at 13:49:08 UTC, MyNameHere wrote:
 Thank you, that seems to have resolved the issue, though I wish 
 these sorts of problems would stop cropping up, they are 
 souring the experience with the language.

Oh and `DevicePath()` is a convenience member returning a pointer 
to the 'dynamic array' (as the array decays to a pointer in C 
too), so no need to fiddle with `.offsetof` and computing the 
pointer manually.

MyNameHere <MyNameHere example.com> writes:

On Friday, 19 August 2022 at 14:30:50 UTC, kinke wrote:
 Oh and `DevicePath()` is a convenience member returning a 
 pointer to the 'dynamic array' (as the array decays to a 
 pointer in C too), so no need to fiddle with `.offsetof` and 
 computing the pointer manually.

I am using ```-BetterC```, so that path is closed to me, I think.

Steven Schveighoffer <schveiguy gmail.com> writes:

On 8/19/22 12:36 PM, MyNameHere wrote:
 On Friday, 19 August 2022 at 14:30:50 UTC, kinke wrote:
 Oh and `DevicePath()` is a convenience member returning a pointer to 
 the 'dynamic array' (as the array decays to a pointer in C too), so no 
 need to fiddle with `.offsetof` and computing the pointer manually.

 
 I am using ```-BetterC```, so that path is closed to me, I think.

dynamic arrays are really slices, and they are allowed in betterC.

-Steve

Tejas <notrealemail gmail.com> writes:

On Friday, 19 August 2022 at 16:36:24 UTC, MyNameHere wrote:
 On Friday, 19 August 2022 at 14:30:50 UTC, kinke wrote:
 Oh and `DevicePath()` is a convenience member returning a 
 pointer to the 'dynamic array' (as the array decays to a 
 pointer in C too), so no need to fiddle with `.offsetof` and 
 computing the pointer manually.

 I am using ```-BetterC```, so that path is closed to me, I 
 think.

I believe you aren't allowed to _append_ to dynamic 
arrays/slices; otherwise you can use them