使用自动工具链接生成的库

Question

I have a following directory structure

src/
    kernel/
    gui/

In kernel/ directory, I have generated a library named libkernel.a and in gui/ directory I have to use libkernel.a to generate libgui.a .

I added this to the gui/Makefile.am

libgui_a_LIBADD = $(srcdir)/kernel/libkernel.a

But I am getting the following error

*** No rule to make target `kernel/libkernel.a', needed by `libgui.a'.  Stop.

So I don't understand how do I link libkernel.a properly.

Edit/Explanation

In gui/ directory I have one somegui.cpp file that uses xclass.h which is in kernel/ directory. So in order to solve that issue I am asking how should I proceed.

Answer 1

Try to use non-recursive automake to avoid these kind of problems.

https://www.flameeyes.eu/autotools-mythbuster/automake/nonrecursive.html

Sidenode: use $(top_builddir) when referring to compiled objects. Otherwise your code will break when srcdir != builddir

If you really have to do it recursive, than you can add a rule to gui/Makefile.am

$(top_builddir)/kernel/libkernel.a:
        cd $(top_builddir)/kernel && $(MAKE)

Note: If you want to use parallel make (-j) you also need to make sure that in src/Makefile.am there is a dependency between the subdirs

.PHONY kernel gui
kernel:
      cd kernel && $(MAKE)
gui: kernel
      cd gui && $(MAKE)