CODEWITHSUNDEEP
c++-cli
Doug Milne
Doug Milne

Reputation: 31

C++/CLI Linker Error LNK2022 when targeting .net5

We are converting a set of C++/CLI projects from vs2017 targeting .netframework 471 to vs2019 targeting .net5.

The following code will compile and link when targeting .netframework471, but will generate a linker error when targeting .net5. Note that it seems to be only the method which uses gcrootSystem::String^, when the method foobar is commented out the project builds and links successfully (meaning that the foobar2 method with the gcrootSystem::Exception^ parameter does not cause a problem).

1>MSVCMRTD_netcore.LIB(mstartup.obj) : error LNK2022: metadata operation failed (80131195) : 1>LINK : fatal error LNK1255: link failed because of metadata errors

// UnmanagedClassWithGcHandle.h
#pragma once
#include <vcclr.h>

class UnmanagedClassWithGcHandle
{
public:
   int age;
   // error LNK2022 : metadata operation failed(80131195) :  ( ONLY TARGETING .NET 5.0 )
   void foobar(gcroot<System::String^>);

   // this is successful
   void foobar2(gcroot<System::Exception^>);
};

#include "pch.h"
#include "UnmanagedClassWithGcHandle.h"

// UnamanagedClassWithCcHandle.cpp
void UnmanagedClassWithGcHandle::foobar(gcroot<System::String^>)
{
}

void UnmanagedClassWithGcHandle::foobar2(gcroot<System::Exception^>)
{
}

Upvotes: 3

Views: 345

Answers (1)

Sean
Sean

Reputation: 62492

I've had exactly the same problem. The problem is with:

#include <vcclr.h>

This is the old file for accessing gcroot. Instead you need to:

#include <msclr/gcroot.h>

This will bring in the gcroot that is in the msclr namespace. Change your code to:

void foobar(msclr::gcroot<System::String^>);

And you should be able to build.

Upvotes: 1

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