CMake build both static and dynamic library

[RSpliet]

For context: to support the work I used to do with SystemC as part of my PhD and since then as a "hobby", for a while now I've had a public Fedora/RedHat/CentOS COPR RPM build repository of SystemC [0]. To generate both the dynamic (.so) library as well as the static (.a) library from the same CMake build, I've always relied on a slightly hacked-up CMakeListst.txt. Unfortunately on every rebase I'd have to re-do the hack, which is why up until today I hadn't done so. On the plus-side, SystemC 3.0.0 makes it easier to perform this hack-up.
Attached to this issue I've attached the patch I've used to achieve both my output files. However, it has two main issues:

1. I probably broke any build that isn't BUILD_SHARED_LIBS on Linux,
2. It compiles all the source files twice. Which is "good enough" for my purposes but not ideal.

So, to support myself on future rebases as well as other (aspiring) distro packager maintainers, I want to request for the CMake builder to support a mode in which it outputs both the .a and the .so from the same build.

[0] https://copr.fedorainfracloud.org/coprs/rspliet/SystemC/
0001-CMakeLists-build-both-static-and-dynamic.zip

[lmailletcontoz]

Thanks for the feedback. Could you propose a Pull Request for further consideration, keeping in mind that the CMake flow shall also support Windows.

[RSpliet]

@lmailletcontoz Thanks for your reply. Truthfully: I don't think I can. I'm afraid I neither have the operating systems (Windows, Mac OS X, various flavours of Linux/BSD?) to test such a change on, nor a good understanding of all the other requirements of the CMake build system to know whether any change I make is good or whether it breaks more than it fixes. This issue is best treated as a feature request. perhaps directed at @pah or anyone who is either better versed in the full SystemC CMake build or better placed to take a deep dive. And since I'm not putting my money where my mouth is, I of course won't be offended if this doesn't get picked up in the end.