"Add as Link" for folders in Visual Studio projects

In Visual Studio, we can "Add as link" to add a link to a file in another project in the solution.

Is there any way to do this for entire folders, so that an entire folder in project A will be visible in project B, without the need to manually link to new items in that folder?

As this blogpost stated, it is possible.

<ItemGroup>
    <Compile Include="any_abs_or_rel_path\**\*.*">
        <Link>%(RecursiveDir)%(FileName)%(Extension)</Link>
    </Compile>
</ItemGroup>

But be aware, the files will not be copied.

In VS2012 and later, you can drag a folder to another project with alt key pressed. It's just the same as adding each file as link manually but faster.

upd: Consider using Shared Projects if you are using VS2013 update 2 (with Shared Project Reference Manager) or VS2015.

One addition to the answer from mo. and the comment from Marcus, if you are linking content items you will need to include the file extension:

<ItemGroup>
  <Compile Include="any_abs_or_rel_path\**\*.*">
    <Link>%(RecursiveDir)%(FileName)%(Extension)</Link>
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </Compile>
</ItemGroup>

Regarding the part of the original query to have a linked folder appear in the IDE, it is kind of possible to achieve this so there is a folder in the solution explorer with all linked files inside, instead of all the files appearing in the root of the solution. To achieve this, include the addition:

  <ItemGroup>
    <Compile Include="..\anypath\**\*.*">
      <Link>MyData\A\%(RecursiveDir)%(FileName)%(Extension)</Link>
    </Compile>
  </ItemGroup>

This will include all files from the linked directory in a new folder in the solution explorer called MyData. The 'A' in the code above can be called anything but must be there in order for the folder to appear.

If you want to add a folder as a reference and you don't want to compile it, use:

<Content Include="any_path\**\*.*">
  <Link>folder_in_B_project\%(RecursiveDir)%(FileName)%(Extension)</Link>
</Content>

Bust out the shell and add a symbolic link.

runas Administrator then

mklink /d LinkToDirectory DirectoryThatIsLinkedTo

BAM symbolic link!

/d specifies directory link.

Works in Vista on up out of the box. Can be backported to XP.

Documentation here: http://technet.microsoft.com/en-us/library/cc753194%28WS.10%29.aspx

For those not familiar with symbolic links, it's essentially a pointer to another file or directory. It's transparent to applications. One copy on disk, several ways to address it. You can also make a "hard link" which is not a pointer to another address, but an actual file ID entry in NTFS for the same file.

NOTE: as stated in the comments, this would only work on the computer where you created the symlink and wouldn't work in a Version Control System like git.