[CMake] Help debug crazy Windows MSVC issue

[Paul Smith]

On Mon, 2014-02-17 at 08:34 -0500, Paul Smith wrote:
> On Mon, 2014-02-17 at 10:20 +0100, Hendrk Sattler wrote:
> > Visual Studio 10 totally relies on the custom build tool to protect 
> > itself when run in parallel.  It will run the generator as many times
> > as the bar.cpp is mentioned in different targets, even in parallel if
> > that is enabled.
> 
> Yes, this matches what I found after sending my last email.

> The problem, of course, is that it uses the exact same .OBJ file to
> link into both the shared and static libraries.  In my real
> environment I'm using different -D* flags, so that doesn't work.

Thanks to all that helped.  I eventually "solved" this problem by
deciding I didn't need this code linked into my static libraries, so I
didn't need to compile the code twice with different flags.

MSVC seems to be stable now... this is a bummer though.

It might be helpful to add this limitation to the docs or a FAQ or
something, for posterity.

Unfortunately I've now run into a problem with Xcode generation which is
at least as concerning.  I'll start a new thread.