Re: Adding CMakeLists.txt files

From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2021-05-28 10:47:47

On 5/28/21 12:42 PM, Niall Douglas via Boost wrote:
> On 28/05/2021 01:12, Peter Dimov via Boost wrote:
> 
>>> How are you handling the repositories which are generated from external
>>> repos? I'm thinking of Outcome and ASIO.
>>
>> I'm not handling them in any way at the moment. But Outcome already has
>> a CMakeLists.txt file, which is largely correct (it's missing a dependency on
>> Boost::throw_exception and there are a few more cosmetic issues that don't
>> really matter.)
> 
> I'm pretty sure Outcome *does* have a dependency on Boost::throw_exception:
> 
> 1. Boost::outcome target link libraries Boost::exception with INTERFACE.
> 
> 2. Boost::exception target link libraries Boost::throw_exception with
> INTERFACE.
> 
> 3. INTERFACE link libraries is transitive, so by describing a dependency
> on Boost::exception, we are declaring a dependency on all the
> dependencies of Boost::exception which includes Boost::throw_exception.
> 
> Now, you may wish every library to *directly* indicate its dependencies
> for some definition of "directly". If that is the case however, then
> Outcome would need to list every second and third order dependency of
> its first order dependencies. That seems brittle to me.

I think, what Peter sees is that you are including 
boost/throw_exception.hpp directly, in boost/outcome/config.hpp, which 
means you have a direct dependency on it.

Second order dependencies need not be specified in CMakeLists.txt, CMake 
will figure those out as it resolves dependencies.