[Boost-build] Handling libraries that are built with external build systems

Subject: [Boost-build] Handling libraries that are built with external build systems
From: Christian Aichinger (caichinger_at_[hidden])
Date: 2016-06-07 09:06:00

Hi!
In a project that uses Boost Build, is there an easy way to have library sub-projects that use other build systems (e.g. CMake)? The resulting .a/.so files should be used by bjam.

E.g.
  ./Jamroot
  ./ext/external-lib/   # built using cmake
  ./lib/internal-lib/   # internal library using bjam
  ./src/                # application code, using both libs
  ...

I tried creating ext/external-lib/Jamfile with the following code:

    notfile build_extlib : @build_extlib ;
    actions build_extlib
    {
        # ... build instructions ...
        touch libextlib.a
    }

    lib extlib : :
        <file>libextlib.a
        : :
        <include>include
        ;

I can then run `bjam ext/external-lib//build_extlib` and use `ext/external-lib//extlib` as library in other targets. However, the build process does not happen automatically. Adding build_extlib as dependency to extlib didn't work, bjam complained about the missing libextlib.a (the build product of build_extlib). I tried using implicit-dependency, but that didn't work either (build_extlib was never executed).

What's the best solution to this problem? Converting extlib to Bjam is not an option, it's a rather involved build system.

Regards,
Chris

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