[CMake] How to build fully correctly versioned shared object files with cmake

[Alexander Neundorf]

On 2018 M08 6, Mon 21:54:33 CEST Hendrik Sattler wrote:
> Am 6. August 2018 20:27:23 MESZ schrieb Philip Van Hoof 
<philip at codeminded.be>:
> >Hello everyone,
> >
> >I noticed that it sometimes happens that I find a package for a shared
> >object file(s) (or DLLs, on platforms like Windows) that have a build
> >set up using cmake, that doesn't set everything that should be set.
> >
> >Usually as packagers of various popular open source softwares correct
> >enthusiasts' attempts at understanding the sometimes bizarre
> >complexities of for example autotools, but (although it's all less
> >complicated) also cmake, it ends up somewhat right. Somewhat. I noticed
> >that especially in corporate world, things tend to go spectacularly
> >wrong. Almost without exception.
> >
> >In particular am I concerned about ABI versioning of shared object
> >files so that they are easy to package and distribute by various
> >operating systems (like, among others, Linux distributions). But also
> >API versioning of development files (compiler header files and pkg-
> >config) and installing to the right installation paths.
> >
> >I wanted to invite the community to scrutinize some equivalent examples
> >that I made for autotools (with libtool), qmake, cmake and meson.
> >
> >https://github.com/pvanhoof/dir-examples/
> >
> >In particular I wanted to invite the cmake community to take a look at
> >this example:
> >
> >https://github.com/pvanhoof/dir-examples/tree/master/cmake-example
> >
> >The idea is that the examples are as correct as possible. That means
> >the examples should simple and educational. Easing (some amount) of
> >platform independence (ie. supporting Windows) and packaging.
> 
> Is there ANY reason to use libtool library versioning? It might surprise
> people but it really is not any kind of standard.
> 
> Just change the SOVERSION when you make incompatible ABI changes and a
> normal library VERSION. There's really not more to it, especially nothing
> like the sick results that libtool produces, sometimes.

I agree.
I would recommend
Major version  = SO version, increase it if you break ABI compatibility
Minor version: increase it if you add ABI compatible features
Patch version: increase it for bug fix releases.

Alex