How to eliminate Warning LNK4221?

Question

I am working on a project using c++/windows forms (visual studio 2010), we have 4 projects:

• 1 project containing GUI windows forms {managed code} and this is the exe project
• other 3 projects {non-managed code} and all are static libraries.
• in the 4 projects we don`t use precompilied headers stdafx.h , and common language runtime support is the Pure MSIL Common Language Runtime Support (/clr:pure).
• every project include the other 3 projects as additional include directories , and link library dependencies set to yes.

We have:

Warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library

This warning appeared for the 3 static libraries projects in the same object files (.NETFramework,Version=v4.0.AssemblyAttributes.obj).

We want to eliminate it, but after some search, most topics speak about the precompiled headers to be a reason while we don not use it.

Any new ideas about why this warning exist and how to eliminate it?

Answer 1

Disclaimer: This solution is indeed terrible, and this code should not be added to production build! It is only useful to "hide" the warning.

A better solution would be to remove the file in question from the compilation, as it is anyway useless.

Original post:

I had a the problem with this warning originating from several dependencies, and I found that it was caused by some translation unit being empty, i.e. empty source files.

These files actually had a content but it was deactivated for visual studio so I just added at the beginning:

__declspec( dllexport ) void getRidOfLNK4221(){}

And now my project compiles without any warning :)

Hope it helps, even if this is a late answer!

Answer 2

I had a c++ static library with an empty module in it, linking which in non-optimized mode gave me that LNK4221 warning. (in Visual Studio) I went to Librarian->All Options, and added "/ignore:4221" to Additional Options. So, the warning has disappeared.

Answer 3

You get this warning because you use only template classes in cpp file. To get rid of it, insert one simple function with no template.

Answer 4

See this: https://learn.microsoft.com/en-us/cpp/error-messages/tool-errors/linker-tools-warning-lnk4221

In summary, the file exports nothing, so linker does not link, as it thinks it's a waste of effort