I have a DLL in D-code which returns an object and want to pass a struct S[] to a member function of that object. The first element is passed correctly, the rest is just garbage. In fact the next item is just a single byte with value 0x11 following some 0x00.

It doesn't matter if I'm using S[], S[]* or S* with .ptr. The length of the array is correct but the data isn't except the first item.

Is this a trap because of extern function? How can I access the next item? Increasing the pointer is equivalent with S[1].

On Monday, 16 November 2020 at 21:31:44 UTC, frame wrote:
> I have a DLL in D-code which returns an object and want to pass a struct S[] to a member function of that object. The first element is passed correctly, the rest is just garbage. In fact the next item is just a single byte with value 0x11 following some 0x00.
>
> It doesn't matter if I'm using S[], S[]* or S* with .ptr. The length of the array is correct but the data isn't except the first item.
>
> Is this a trap because of extern function? How can I access the next item? Increasing the pointer is equivalent with S[1].

What is the function prototype like and how are you declaring that struct?

On Monday, 16 November 2020 at 21:58:44 UTC, Jack wrote:

> What is the function prototype like and how are you declaring that struct?

The struct is very simple, it contains:

struct S {
    SysTime a;
    ulong b;
    double c;
    ubyte[] d;
    string e;
}

And I tried:

bool foo(S[] params);     // passing a S[]
bool foo(S[]* params);    // passing a &S[]
bool foo(S* params);      // passing a S.ptr

On Monday, 16 November 2020 at 22:22:42 UTC, frame wrote:
> On Monday, 16 November 2020 at 21:58:44 UTC, Jack wrote:
>
>> What is the function prototype like and how are you declaring that struct?
>
> The struct is very simple, it contains:

I found the "bug". It was caused by a debug {} statement within a struct method. I assume that the debug symbol is just incompatible called from the DLL context.

On Wednesday, 18 November 2020 at 10:50:12 UTC, frame wrote:
> I found the "bug". It was caused by a debug {} statement within a struct method. I assume that the debug symbol is just incompatible called from the DLL context.

Were the DLL and main program built in different modes (debug/release)? Then this problem is understandable. Otherwise I find this surprising, and probably worth a bug report?

— Bastiaan.

On Thursday, 19 November 2020 at 07:46:20 UTC, Bastiaan Veelo wrote:
> On Wednesday, 18 November 2020 at 10:50:12 UTC, frame wrote:
>> I found the "bug". It was caused by a debug {} statement within a struct method. I assume that the debug symbol is just incompatible called from the DLL context.
>
> Were the DLL and main program built in different modes (debug/release)? Then this problem is understandable. Otherwise I find this surprising, and probably worth a bug report?
>
> — Bastiaan.

No, but the DLL was compiled with -debug flag which enables an additional member that the main program cannot see. I think that is the explaination. In fact the flag was not set on the main program.