Greetings!

From time to time I encountered issues on the subjected after I upgraded my dmd package.Given below code :

import core.sys.windows.windows;
import core.sys.windows.commdlg;
import core.sys.windows.winuser;

extern(Windows) BOOL GetOpenFileNameW(LPOPENFILENAMEW);
extern(Windows) int MessageBoxW(HWND,LPCWSTR,LPCWSTR,UINT);

void main()
{
	wchar[256] fileName;
	fileName[0]=0;
	OPENFILENAMEW ofn;
	
	ofn.lStructSize=OPENFILENAMEW.sizeof;
	ofn.lpstrFilter=
	"Text Files\0*.txt\0 D files\0*.d;*.di\0\0"w.ptr;
	ofn.lpstrFile=fileName.ptr;
	ofn.nMaxFile=fileName.length;
	if(GetOpenFileNameW(&ofn))
	{
		MessageBoxW(null,ofn.lpstrFile,"File Selected:"w.ptr,0);	
	}
}

The compiler failed to build this small program.It complains GetOpenFileNameW & MessageBoxW are unresolved external symbol.

DMD 2.103+VS Community 2015+Win10 64bit.

estwinapi.obj : error LNK2019: 无法解析的外部符号 _GetOpenFileNameW@4，该符号在函数 __Dmain 中被引用
testwinapi.obj : error LNK2019: 无法解析的外部符号 _MessageBoxW@16，该符号在函数 __Dmain 中被引用
testwinapi.exe : fatal error LNK1120: 2 个无法解析的外部命令

Error: linker exited with status 1120

Appreciated any help on figuring me out what the issue is and how to fix it.

On Thursday, 2 November 2023 at 08:31:41 UTC, Peter Hu wrote:

void main()
{
	wchar[256] fileName;
	fileName[0]=0;
	OPENFILENAMEW ofn;
	
	ofn.lStructSize=OPENFILENAMEW.sizeof;
	ofn.lpstrFilter=
	"Text Files\0*.txt\0 D files\0*.d;*.di\0\0"w.ptr;
	ofn.lpstrFile=fileName.ptr;
	ofn.nMaxFile=fileName.length;
	if(GetOpenFileNameW(&ofn))
	{
		MessageBoxW(null,ofn.lpstrFile,"File Selected:"w.ptr,0);	
	}
}

Works for me.

But you don't need to declare the functions, they are already declared in commdlg and winuser.

import core.sys.windows.windows;
import core.sys.windows.commdlg;
import core.sys.windows.winuser;

void main()
{
	wchar[256] fileName;
	fileName[0]=0;
	OPENFILENAMEW ofn;
	
	ofn.lStructSize=OPENFILENAMEW.sizeof;
	ofn.lpstrFilter=
	"Text Files\0*.txt\0 D files\0*.d;*.di\0\0"w.ptr;
	ofn.lpstrFile=fileName.ptr;
	ofn.nMaxFile=fileName.length;

	if(GetOpenFileNameW(&ofn))
	{
		MessageBoxW(null,ofn.lpstrFile,"File Selected:"w.ptr,0);	
	}
}

On Thursday, 2 November 2023 at 09:01:06 UTC, Imperatorn wrote:

This is all you need

import core.sys.windows.commdlg;
import core.sys.windows.winuser;

void main()
{
	wchar[256] fileName;
	OPENFILENAMEW ofn;

	ofn.lStructSize = OPENFILENAMEW.sizeof;
	ofn.lpstrFilter = "Text Files\0*.txt\0 D files\0*.d;*.di\0\0"w.ptr;
	ofn.lpstrFile = fileName.ptr;
	ofn.nMaxFile = fileName.length;

	if (GetOpenFileNameW(&ofn))
	{
		MessageBoxW(null, ofn.lpstrFile, "File Selected:"w.ptr, 0);
	}
}

On Thursday, 2 November 2023 at 08:31:41 UTC, Peter Hu wrote:

If it still doesn't work try adding this:

pragma(lib, "user32");
pragma(lib, "comdlg32");

On Thursday, 2 November 2023 at 09:08:02 UTC, Imperatorn wrote:

pragma(lib, "user32");
pragma(lib, "comdlg32");

Another alternative if you're using dub is to add this in your dub.json instead:

"libs": ["user32", "comdlg32"]

This seems be something related to DMD vs LDC. Because if I change the compiler to DMD I also get unresolved external symbols, but not with LDC.

It seems the forwarding of directives from submodules are different.

On Thursday, 2 November 2023 at 09:13:11 UTC, Imperatorn wrote:

pragma(lib, "user32");
pragma(lib, "comdlg32");

"libs": ["user32", "comdlg32"]

Below two pragma solved the isse but am confused as they are already in the system path.This is the first time I have to include lib files here.How come other gui programs don't have to do this.
pragma(lib,"user32");
pragma(lib,"comdlg32");

On Thursday, 2 November 2023 at 09:58:21 UTC, Peter Hu wrote:

pragma(lib, "user32");
pragma(lib, "comdlg32");

"libs": ["user32", "comdlg32"]

I'm not sure why, it works for me, but I think it could be something dmd does different. The pragma lib is inserted into the generated object file, or otherwise passed to the linker, so the linker automatically links in that library.

I'm guessing dmd for some reason does not see it in the submodule, but I have no proof that's the issue, I'm just guessing.

On Thursday, 2 November 2023 at 10:02:29 UTC, Imperatorn wrote:

pragma(lib, "user32");
pragma(lib, "comdlg32");

"libs": ["user32", "comdlg32"]

Really appreciated for the help.I am learning to understand.
Not using these two pragma in the source,other in the commandline:dmd -m64 user32.lib comdlg32.lib test.d compiled.But---
In an IDE say PoseidonD it still failed to compile even if I provided the library path to the compiler,I just can't understand how come my other small programs ( based on gui libslike DFL2,iup4D,dwt,NAppGui4D ) works fine without having to provide pragma in the source before compiling.

On Thursday, 2 November 2023 at 10:17:37 UTC, Peter Hu wrote:

"libs": ["user32", "comdlg32"]

I'm sorry, I don't know. I have just observed that when using LDC the libraries gets forwarded from submodules but not with DMD.

So what I usually do is to add them in my dub.json "libs" property as shown before.

Oh my, I didn't know poseidon still existed :D

Is this what you're using?
https://bitbucket.org/KuanHsu/poseidond

I currently use vscode and Visual D, they both work good.

But it's always fun to see other IDEs

On Thursday, 2 November 2023 at 10:17:37 UTC, Peter Hu wrote:

pragma(lib, "user32");
pragma(lib, "comdlg32");

"libs": ["user32", "comdlg32"]

It's probably because these libraries already have the symbols