[CMake] CMake Error: install(EXPORT "A" ...) includes target "b" which requires target "c" that is not in this export set, but x times in others.

[Nico Schlömer]

Hi all,

in on CMake project of mine, all seems to configure fine until the
very end where I'm getting error messages like
```
CMake Error: install(EXPORT "A" ...) includes target "b" which
requires target "c" that is not in this export set, but x times in
others.
```
First of all, CMake does seem to create all files necessary for
building the project, since that goes without error. Hence, I'm not
really sure CMake yells at me.
Second, I don't really understand the message. Indeed, I have a couple
of export sets in my project, and the libraries there in depend on
each other. Why the target "c" need to be in the same export set as
"b"?

This is with CMake 2.8.12.2.

Cheers,
Nico