[CMake] ExternalProject_Add show sources in Visual Studio

[David Cole]

Well, that sounds like the perfect way to use ExternalProject.

But why do you want to show the sources in Visual Studio? Just for ease 
of looking at them?

As I said in my earlier reply... even if we showed the sources, editing 
them would not trigger a rebuild of the external project. The 
dependencies are tracked via custom commands and stamp files that 
indicate last successful run time of those custom commands. They are 
not tracked by Visual Studio on a per-source-file/per-obj-file basis as 
they are in a normal VS project.

The main goal of ExternalProject is to provide an easy-to-use way of 
*building*, *installing* and depending on an external project... It is 
most definitely NOT to provide an easy way to do active development on 
a project.

If you need to see the sources for something that you're building 
within Visual Studio, then to me, that's a big red flag that it should 
not be an external project.


HTH,
David C.