How does Copy-local work? log4net.dll is not being copied to MyProject output directory

Question

I am wondering what copy-local=true for references exactly does. Does it copy the referenced assembly along with all of its dependencies to the output directory?

My scenario is the following: I have a custom log wrapper that utilizes log4net. I build a release assembly of MyLogWrapper.dll with log4net.dll reference set to copy-local true. Referencing MyLogWrapper.dll from MyProject with copy local set to true should result in log4net.dll being copied as well right? I am only referencing MyLogWrapper.dll and none of its dependencies in MyProject. log4net.dll is not being copied to MyProject output directory but all other dependencies of MyLogWrapper are. What could be the problem?

I have made some more experiments and it seems that if I remove the assembly (log4net.dll) from GAC it starts to get copied locally. Can anyone confirm that this is the problem?

Answer 1

Unfortunately it appears that according to the following statement taken from the MSDN documentation the CopyLocal functionality does not work as expected for assemblies already in the GAC.

If you deploy an application that contains a reference to a custom component that is registered in the GAC, the component will not be deployed with the application, regardless of the CopyLocal setting. In previous versions of Visual Studio, you could set the CopyLocal property on a reference to ensure that the assembly was deployed. Now, you must manually add the assembly to the \Bin folder. This puts all custom code under scrutiny, reducing the risk of publishing custom code with which you are not familiar.

More information can be found at the following page which explains details about how project references work.

MSDN: Project References

Answer 2

After asking this question on MSDN here - it seems that this behaviour is by design. "If you deploy/copy an application that contains a reference to a custom component that is registered in the GAC, the component will not be deployed/copied with the application, regardless of the Copy Local setting."