[CMake] Looking for an explanation: What exactly means "install" in cmake language?

[Eric Noulard]

Le lun. 7 oct. 2019 à 16:49, Cornelis Bockemühl <cornelis at bockemuehl.ch> a
écrit :

> Thanks to both you and J Decker: I would say that this is still the part
> that I understood! So basically the word "install" in cmake language could
> be replaced by "copy" more or less in common human language - right?
>

Nope I oversimplified.
This is not a bare copy, e.g. the runtime path (a.k.a. RPATH or RUNPATH) is
updated as well.

But then, if it is about "installing" a "target", which is libraries in my
> case, I would expect the shared libraries to be copied - no?
>

Yes the shared lib should be coped and its RPATH updated.


> And this is exactly what does not happen - for no obvious reason! Because
> some days ago it even happened in my project ONCE - and then not any more.
> But debugging is not easy because since that moment I changed many things,
> and basically the reason for my question is that I have no clear idea what
> EXACTLY should happen if I put a
>
> install(TARGETS mylibrary)
>
> into my CMakeLists.txt. Well, like you explained, and like what I also
> thought I had understood: nothing should happen during the configure and
> generate runs of cmake, and also not during the "ninja all" build run, but
> only during the "ninja install". or else cmake --build . --target install
> (which in turn calls ninja in my case). Indeed I observed that it does a
> build for "all" first if the initial project is not up to date.
>
> But then it tells me that it is successfully "installing" mylibrary, but I
> see no shared library appearing in the install tree! Or rather: it happened
> once, but not any more - and I should find out what is missing...
>

.
Are building out-of-tree? (Are your source tree and build tree separate
dir?)
If so, did you try removing the entire build tree and try again ?


May be there is probably some mixup with your install DESTINATION in your
install command.

>
> My current workaround is indeed that I am trying to avoid the install step
> altogether and build a crazy construction with configure_file stuff in
> order to get the libraries to the right place - and I know pretty well that
> this is NOT the way how things should be done properly. But I am afraid I
> will be ready with this workaround way faster than I will understand what
> is going on during this miraculous "install" process!


Provide us with a stripped down non-working example and we may dig into it.
Otherwise it is very difficult to guess what is happening in your
particular case.


-- 
Eric
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