Re: cmake support

[Kamil Dudka]

On Tuesday, January 8, 2019 2:46:08 AM CET Andrew Pennebaker wrote:
> Hmm, cmake clearly supports building *libraries and executables* for
> non-cmake external projects. But in the case of gnulib, gnulib itself does
> not emit a library or executable, right?

gnulib builds a static library.  I thought it was obvious from my first reply.

> It's meant to be sourced inside of another autotools project.

Yes but a workaround exists and I mentioned it in my first reply.  Did you
try it?

Kamil

> Can cmake really be integrated around gnulib, or
> am I forced to rewrite my project's build system in terms of autotools?
> 
> Specifically, could someone clarify how gl_EARLY is supposed to be triggerd
> by cmake in the inner gnulib project, so that files like openat.h can be
> sourced from the cmake outer project? I don't know enough about autoconf
> yet to understand how cmake would do this. It's hard enough getting this
> far:
> 
> # CMakeLists.txt
> # Doesn't even work on my machine^TM
> 
> add_executable(fewer lib/main.c lib/fewer.c)
> 
> if(CMAKE_SYSTEM_NAME MATCHES "Minix")
>   ExternalProject_Add(
>     gnulib
>     SOURCE_DIR "gnulib"
>     CONFIGURE_COMMAND "${PROJECT_SOURCE_DIR}/gnulib/gnulib-tool" --dir
> "${PROJECT_SOURCE_DIR}/gnulib-prefix/src/gnulib-build" --import openat # &&
> autoreconf -i && ./configure
>     BUILD_COMMAND echo
>     INSTALL_COMMAND echo
>   )
>   add_dependencies(fewer gnulib)
>   target_include_directories(fewer PUBLIC
> gnulib-prefix/src/gnulib-build/lib)
>   target_link_libraries(fewer libgnu)
> endif()
> 
> On Sun, Jan 6, 2019 at 3:37 AM Kamil Dudka <address@hidden> wrote:
> > On Sunday, January 6, 2019 3:22:01 AM CET Andrew Pennebaker wrote:
> > > Ach, I've made a career out of not having to know autotools! ./configure
> > 
> > &&
> > 
> > > make && [sudo] make install were black boxes as far as I was concerned.
> > > 
> > > So be it, I'll spend some time reading up this weekend and see how far I
> > > get. MSVC integration will become more interesting, but I suppose I can
> > > disable Gnulib for targets that don't actually need it. This is what I
> > 
> > get
> > 
> > > for dipping my toes in CloudABI and introducing dprintf(), openat() to
> > > my
> > > projects :P
> > > 
> > > Would be nice to offer NetBSD-style packages for MINIX and SmartOS, in
> > > order to make Gnulib easier to install to a standard include path like
> > 
> > with
> > 
> > > other development libraries.
> > 
> > I am afraid that there is no OS distribution that would install Gnulib to
> > a standard include (and library) path and this is most likely not going to
> > change because gnulib's developers do not want gnulib to be used this way:
> > 
> > 
> > https://www.gnu.org/software/gnulib/manual/html_node/Library-vs-Reusable-C
> > ode.html#Library-vs-Reusable-Code
> > 
> > Kamil
> > 
> > > On Sat, Jan 5, 2019 at 12:31 PM Kamil Dudka <address@hidden> wrote:
> > > > On Saturday, January 5, 2019 6:53:06 PM CET Bruno Haible wrote:
> > > > > Hi,
> > > > > 
> > > > > Andrew Pennebaker wrote:
> > > > > > Could we improve how gnulib integrates with downstream projects,
> > > > > > to
> > > > 
> > > > make
> > > > 
> > > > > > it
> > > > > > easier to work with different build tools? In particular, would be
> > > > 
> > > > helpful
> > > > 
> > > > > > for gnulib to easily work with cmake projects.
> > > > > > 
> > > > > > In my case, I have an application that needs openat(), and I
> > 
> > already
> > 
> > > > have
> > > > 
> > > > > > a
> > > > > > complex cmake configuration that would be difficult to rewrite in
> > > > 
> > > > terms of
> > > > 
> > > > > > autotools.
> > > > > 
> > > > > I don't think we will spend time to make gnulib-tool generate cmake
> > > > > configurations.
> > > > > 
> > > > >   1. Because the GNU build system is based on Autotools.
> > > > >   2. Because many people say that cmake is a horror to use. [1][2]
> > > > 
> > > > That is not an argument.  You can find similar horror stories about
> > > > 
> > > > autotools:
> > > >     http://voices.canonical.com/jussi.pakkanen/2011/09/13/autotools/
> > > > > 
> > > > > But gnulib-tool by design creates a subdirectory, and you can
> > 
> > yourself
> > 
> > > > >   - add a simple configure.ac to that subdirectory, as outlined in
> > 
> > the
> > 
> > > > >     documentation [3],
> > > > 
> > > > When I needed it 10 years ago, I was able to get around this
> > 
> > limitation by
> > 
> > > > using the --create-testdir option of gnulib-tool.  It created a
> > 
> > directory
> > 
> > > > with configure script that (after running make) produced a static
> > 
> > library.
> > 
> > > > I am not sure if this approach had any side effects, like turning on
> > 
> > debug
> > 
> > > > build, but I was at least not forced to create configure.ac etc.
> > > > 
> > > > Kamil
> > > > 
> > > > >   - integrate this subdirectory with cmake through an
> > 
> > 'ExternalProject'
> > 
> > > > [4].
> > > > 
> > > > > If, during this process, you encounter pain points that require
> > 
> > (small)
> > 
> > > > > gnulib-tool changes, please come back to us and report them.
> > > > > 
> > > > > Bruno
> > > > > 
> > > > > [1]
> > 
> > https://www.reddit.com/r/cpp/comments/4flb8z/fighting_through_a_cmake_hell
> > 
> > > > /
> > > > 
> > > > > [2]
> > 
> > https://www.reddit.com/r/cpp/comments/7yps20/its_time_to_do_cmake_right/
> > 
> > > > > [3]
> > 
> > https://www.gnu.org/software/gnulib/manual/html_node/Initial-import.html
> > 
> > > > > [4]
> > 
> > https://stackoverflow.com/questions/5971921/building-a-library-using-autot
> > 
> > > > o
> > > > 
> > > > > ols-from-cmake