[CMake] Need ideas/opinions on third party library management

[Robert Dailey]

Wow I actually completely forgot about that lol. I think I was looking
into it for some other reasons, not related to work. I will have to
look into it again. I don't really remember much about it.

Thanks for the reminder.

On Sat, Aug 13, 2016 at 7:02 PM, Ruslan Baratov
<ruslan_baratov at yahoo.com> wrote:
> Hi, Robert
>
> According to your GitHub account you've send a trivial patch about a year
> ago to the Hunter (https://github.com/ruslo/hunter) package manager. So I
> wonder what is your experience, have you tried it? Have you run into some
> troubles?
>
> Thanks, Ruslo
>
>
> On 12-Aug-16 22:59, Robert Dailey wrote:
>>
>> Hello,
>>
>> There is an internal C++ product at the company I work for which I
>> have written a series of CMake scripts for. This project actually has
>> dependencies on several open source libraries, such as boost,
>> freetype, openssl, etc.
>>
>> Right now what we do is build each of these third party libraries *by
>> hand*, once for every platform we support (Windows, Linux x86, Android
>> NDK). Then we stuff the includes (headers) and libraries
>> (static/shared) in a submodule and the primary code base's CMake
>> scripts pull them in as interface targets.
>>
>> This works well and is light-weight but is a pain when upgrading or
>> changing libraries. It's a pain because if I want to upgrade boost, I
>> have to build it up to 6 times (once for each platform and once for
>> each configuration).
>>
>> I've been thinking of a different approach for a while. I've done some
>> toying around with the "Super Build" concept, where I have a separate
>> CMake project that does nothing but use the ExternalProject module to
>> build libraries in real time along with our project. So the order of
>> operations would be as follows (for our automated build server):
>>
>> 1. Clone our "Third Party" repository
>> 2. Use CMake to generate & build the "Super Build" project (this
>> builds boost, openssl, freetype, etc for the current platform).
>> 3. Clone the main code base's repository
>> 4. Use CMake to generate & build, using find_package() to refer to
>> interface targets exported by those third party libraries built in
>> step 2
>>
>> Obviously this will make builds take significantly longer, because
>> we're constantly rebuilding the same third party libraries over and
>> over again. However, it virtually eliminates the maintenance burden
>> for third party libraries because they are built inherently with
>> everything else.
>>
>> Note that I can't refer to pre-built libraries in our build
>> environments because we need very specific control over the versions
>> of our libraries as well as the toolchains that were used to build
>> them. Also we may specifically build our libraries a certain way (such
>> as boost). For this reason we do not rely on our external environment
>> or external package managers to fulfill third party dependencies, like
>> most open source projects do on Linux for example.
>>
>> Does this "Super Build" approach sound like a better idea? What other
>> options are available? The downside with the "Super Build" solution is
>> that it will become very difficult to make the transition between
>> building third party and building our code base seamless. I can't do
>> both in the same generate step because find_package() can't be called
>> until the libraries are built & installed.
>
>
>