LNK2019 error in the C++ interface

Sep 03, 2020

dokutoku

Jun 10, 2021

dokutoku

Jun 10, 2021

Mike Parker

Jun 10, 2021

kinke

Jun 16, 2021

dokutoku

I tried to use a function from a library written in C++ in D. I've been trying to use it in D. But I got an error in LNK2019 and the build failed. So I created a simple static library as follows and built it. ```cpp #pragma once #include <windows.h> namespace static_test { void str_test(LPCSTR str) { MessageBoxA(NULL, str, NULL, MB_OK); } void wstr_test(LPCWSTR str) { MessageBoxW(NULL, str, NULL, MB_OK); } void rect_test(RECT rect) { } } ``` ```d import core.sys.windows.windows; import std.utf; extern (C++, "static_test") { nothrow @nogc extern void str_test(LPCSTR str1); nothrow @nogc extern void wstr_test(LPCWSTR str1); nothrow @nogc void rect_test(RECT rect); } void main() { str_test(toUTFz!(const char*)("test")); // error LNK2019 wstr_test(toUTF16z("test"w)); // error LNK2019 rect_test(RECT.init); } ``` The LNK2019 error still occurred. I'm guessing that the reason for the error is that the type declared in C++ is different from the type declared in D. But I'm not sure how to fix it.

June 10, 2021

Re: LNK2019 error in the C++ interface

Posted by dokutoku
in reply to dokutoku

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dokutoku

Posted in reply to dokutoku

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It's been a while since then, but the problem with the structure has been solved.
The reason seems to be that the structure name defined in core.sys.windows.windef was not tagRECT.
I was able to get it to compile by adding a custom definition as follows

extern (C)
struct tagRECT
{
	LONG left;
	LONG top;
	LONG right;
	LONG bottom;
}

alias RECT = tagRECT;

The type name did not work.
The reason seems to be that WCHAR should be mangled with wcha_t, but it is mangled with chat16_t.
Since the mangle is wchat_t, I thought maybe I should use wchar_t in core.stdc.stdef, so I changed LPCWSTR to const (wchar_t)*, but that didn't work either.

I still haven't solved this problem.
I also took a look at Data Type Compatibility in Interfacing to C++, and I think it's wrong about wchar_t.

https://dlang.org/spec/cpp_interface.html#data-type-compatibility

On Thursday, 10 June 2021 at 15:19:27 UTC, kinke wrote: > Confirmed: https://issues.dlang.org/show_bug.cgi?id=22014 Thank you for the bug report. I'm glad I couldn't handle it myself. The only thing that bothers me is that there is no sign of this problem being fixed. I fear that this may be the case forever. On Thursday, 10 June 2021 at 15:19:27 UTC, kinke wrote: > Wrt. `tagRECT`, this should come in handy (for a druntime fix): https://dlang.org/changelog/2.097.0.html#pragma-mangle-aggregate I don't see how this helps with the modifications related to tagRECT.

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