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

[Ruslan Baratov]

On 16-Aug-16 13:52, Florent Castelli wrote:
> For example, Boost is used by 5 platforms: Windows, OSX, Linux, Android and iOS.
> Each platform has a different CPU target (or many 32/64bit, x86/ARM).
> Each platform has many compilers.
> Some platforms have instrumentation options (Debug / Release, ASan, MSan…) and really need
> to be compiled properly, otherwise you’ll end up with false positives.
> The matrix of builds is REALLY hard to track. Each time we update Boost, we had to update
> a lot of things.
Not a problem for Hunter.

Linux, OSX, Windows, iOS 9.3, iOS 8.2, Android, GCC, Clang, ASan, 
LeakSan, ThreadSan, Static Analyzer,  libstdc++, libc++, MinGW, Visual 
Studio 2008-2015:
* https://travis-ci.org/ingenue/hunter/builds/140317830
* https://ci.appveyor.com/project/ingenue/hunter/build/1.0.665

This list is not even full, I guess I can add more toolchains in future 
(GCC variations and C++ standards).

To test all matrix I need to push one commit to pkg.boost branch, to 
upload binaries to server I need to push one commit to upload.boost 
branch (upload ALL toolchains at one shot). To reuse all updates users 
just need to set new URL/SHA1 of HunterGate module: 
https://github.com/ruslo/hunter/releases

> Overall, building boost takes 10s on our developers’ machines. The sources aren’t changed often,
> so the cost is pretty low.
What kind of hardware do they have? And what libraries you mean? It 
takes about 20 seconds on my Linux machine just to unpack 80 MB of Boost 
release archive. It's even worse on Windows, it takes several minutes 
for some strange reason even on SSD + Core i7. Using binaries in such 
cases is a huge time saver because there is no need to compile anything 
and there is no a lot of junk that they put into release archive (if you 
remove docs and tests 80 MB became 15 MB).

Of course building from source is not an option for such monsters like 
Qt or OpenCV. Ready-to-use binaries is something critical for real life 
applications. There is no way to test everything on Travis/AppVeyor 
without this feature.

Ruslo