I am using a makefile system with the pvcs compiler (using Microsoft Visual C++, 2008 compiler) and I am getting several link errors of the form:
error LNK2019: unresolved external symbol __imp__RegisterFilter@8 referenced in function _main
This is happening DESPITE using the extern "C"
declaration, viz.:
extern "C" int CLRDUMP_API RegisterFilter( LPCWSTR pDumpFileName, unsigned long DumpType );
Also, in the makeexe.mak, the library is being linked in as:
$(COMPILEBASE)\lib\clrdump.lib \
To be honest, I am not an expert at makefiles, and I am changing over a system from Microsoft Visual C++ 6.0 to 2008. This change-over may have something to do with the link errors, as the system used to work before.
Any help would really be appreciated.
Thanks in Advance,
Sincerely, Joseph
-- Edit 1 --
Does anyone know how to turn verbose on in the makefile system of pvcs?
Note that the above function is already a compiler-decorated version, having
__imp__RegisterFilter@8
whereas the C++ function is just
RegisterFilter
Thanks for the help, but if anyone can post a more complete solution, that would also be very appreciated.
Sincerely, Joseph
-- Edit 2 --
Some kind person posted this, but when I signed in it disappeared:
The imp prefix indicates that this function is imported from a DLL. Check the definition of CLRDUMP_API
- is it __declspec(dllimport)
? See this article for more information.
There was a working link, but I've lost that, however I suppose one can always search the topic.
Thanks, whoever you were!
-- Edit 3 --
Thanks ChrisN (I'm not yet allowed to vote). Despite using the refresh button, your answer disappeared, but then re-appeared after I posted a cut-n-paste.
This is my definition of that:
define CLRDUMP_API __declspec(dllimport) __stdcall
I assume that the __stdcall is OK?
-- Edit 4 --
While I appreciate the efforts of those who answered, particularly ChrisN, at least on my particular system, the link error remains. So if anyone has any further insight, I'd appreciate it. Thanks again.
Try turning on verbose output for your linker (typically a command-line switch). That will show you exactly how the linker is trying to resolve the symbol, so you can see if:
I hope this helps!
Don't know if it is your case, but the imp prefix may mean that you are compiling a x64 library in a Win32 project.
I was creating a simple Win32 c++ application in VS2005 and I was getting this error:
This application was using property sheets, hence it required this header (prsht.h).
The solution to my problem was as follows: in program Properties→Configuration Properties→Linker→General, I set Additional Library Directories to
"C:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\Lib"
.Also in program Properties→Configuration Properties→Linker→Command line for the Additional Options, I added
ComCtl32.Lib ComDlg32.Lib
.My program is now compiling without any problems. My two cents: you need to identify all the libraries that your program requires. Hint: check all the headers you have included, you need to make sure that your linker can see them.
I recently had the same problem. I was excluding a library to avoid a collision, and all the bugs went away, except for LINK errors (just as you describe). When I swapped the library for the other one (I was excluding (ignoring) MSVCRT.lib, now I'm excluding (ignoring) LIBCMT.lib) the problem disappeared. Make sure you have not mixed libraries up somewhere. In my case, the linker was failing with "can't find imp_aligned_malloc". Of course there was no method in any of my code by that name. The compiler was prepending the imp. Exactly why I don't know, except that the problem went away when I swapped the exclude (ignore) as described above.
Try starting with a fresh project, and re-add your source & header files, and keep track of the libraries you exclude (ignore). Try various combinations. Hope that helps.
Using a .DEF File
If you choose to use __declspec(dllimport) along with a .DEF file, you should change the .DEF file to use DATA or CONSTANT to reduce the likelihood that incorrect coding will cause a problem:
The following table shows why:
http://msdn.microsoft.com/en-us/library/aa271769(v=vs.60).aspx
The
__imp_
prefix indicates that the linker expects this function to be imported from a DLL.Is the clrdump library from this page? If so, note that
extern "C"
is not used in the header file supplied with the library. I confirmed this using the following command:which produces the following output for
RegisterFilter
- this is a mangled C++ function name:I tried creating a sample program using clrdump.lib using Visual Studio 2008. Here's my code:
Building this produced the following linker error:
The code builds OK with Visual C++ 6.0.
Notice that the
dumpbin
output shows the first parameter toRegisterFilter
asunsigned short const *
but the linker error showswchar_t const *
. In Visual C++ 6.0,wchar_t
is normally a typedef forunsigned short
, whereas in later versions it is a distinct built-in type.To work around the problem in Visual Studio 2008, I set the "Treat wchar_t as Built-in Type" option to "No" (specify
/Zc:wchar_t-
on the compiler command line), and the code now builds OK.Sorry for the confusion with my previous answer. I hope this is more helpful!