Linking libraries during build vs. install



  • Hello all. I have a problem regarding linking of shared libraries (I'll refer to them as .so files since I'm on linux).
    Let's say I have project A and project B. Project A builds as an executable file and project B builds as a .so

    My project tree looks like this:

    • Root
      • A
      • B

    And this is also what it looks like in my build directory.
    These projects installs to /usr/bin and /usr/lib respectively.

    Now, how do I go about to make it so that I can link to the installed version of project B (i.e. /usr/lib/B.so) when I compile project A?

    The chain of operations look like this: build B, build A, install B, install A.
    But if I declare LIBS += -L/usr/lib -lB in project A, it will look for the installed library, which isn't there during compile.

    Should I declare something like LIBS += -L<buildDirectory>/lib -L/usr/lib -lB?

    I'm sorry if this is too incoherent, but I hope someone will understand my problem!


  • Lifetime Qt Champion

    Hi,

    If you install B after compiling A you have to link A to the B library in the build directory simply because B is not yet installed. And you'd better do this anyway, since if you change B and want to relink A to B, it would link to the installed and not newly built B.

    To sum up:

    @LIBS += -L<buildDirectory>/lib -lB@

    Otherwise you have to build B, install B, build A, install A


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