[cmake-developers] Add property to get all linked libraries including transitive ones

[Florent Castelli]

One usage I would have had for this feature would have been to generate 
a pre-linked library.
Basically, merging a static library and its dependencies together (check 
ld -r) and output an object file for static linking (not a shared library).
This is required as merging static libraries may conflict on filenames 
in the archive (they could be renamed though) or generate huge archives 
(hey, here's 1000 copies of std::string and std::vector methods and 
their debug symbols).

Instead, I recursed on all the dependencies to generate an extra build 
step to merge everything. The file is small and can be cached.
We did that to save time for our iOS devs so they didn't have to rebuild 
our big C++ library all the time. We targeted iOS 7, so shared libraries 
were not available.

It's a bit more involved, but it would have been useful. Though, I 
understand it can be tricky to get the on-disk path to a library with 
all generators (we had 2 code paths, one for Xcode builds and another 
one for Ninja).

/Florent

On 02/11/2016 12:56, Brad King wrote:
> On 11/01/2016 04:30 PM, maikel van den Hurk wrote:
>> obtain actually all transitive linked libraries of a specific target.
> [snip]
>> this information is only fully available during generation time.
> What is an example use case for this?  I don't think we can offer a
> configure-time solution but perhaps there is a generate-time solution
> to the use case.
>
> -Brad
>