Add depexts to the package.

[eriklovlie]

Tried to get one of my projects to build on a new computer, but for some reason it failed due to not being linked to libGL. Then I tried the tgls example program "trigl4.ml" and this had the same issue:

$ ocamlfind ocamlopt -linkpkg -package result,tsdl,tgls.tgl4 -o trigl4.native trigl4.ml
$ ldd ./trigl4.native 
	linux-vdso.so.1 (0x00007fffc3b59000)
	libSDL2-2.0.so.0 => /lib64/libSDL2-2.0.so.0 (0x00007f4c1ee6c000)
	libffi.so.6 => /lib64/libffi.so.6 (0x00007f4c1ec63000)
	libm.so.6 => /lib64/libm.so.6 (0x00007f4c1e8cf000)
	libdl.so.2 => /lib64/libdl.so.2 (0x00007f4c1e6cb000)
	libc.so.6 => /lib64/libc.so.6 (0x00007f4c1e30c000)
	libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f4c1e0ed000)
	librt.so.1 => /lib64/librt.so.1 (0x00007f4c1dee5000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f4c1f19b000)

I tried to pass "-lGL" directly and it then worked:

$ ocamlfind ocamlopt -cclib '-lGL' -linkpkg -package result,tsdl,tgls.tgl4 -o trigl4.native trigl4.ml
$ ldd ./trigl4.native 
	linux-vdso.so.1 (0x00007fffc19f5000)
	libSDL2-2.0.so.0 => /lib64/libSDL2-2.0.so.0 (0x00007fc244770000)
	libffi.so.6 => /lib64/libffi.so.6 (0x00007fc244567000)
	libGL.so.1 => /lib64/libGL.so.1 (0x00007fc2442d6000)
	libm.so.6 => /lib64/libm.so.6 (0x00007fc243f42000)
	libdl.so.2 => /lib64/libdl.so.2 (0x00007fc243d3e000)
	libc.so.6 => /lib64/libc.so.6 (0x00007fc24397f000)
	libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fc243760000)
	librt.so.1 => /lib64/librt.so.1 (0x00007fc243558000)
	libGLX.so.0 => /lib64/libGLX.so.0 (0x00007fc243326000)
	libX11.so.6 => /lib64/libX11.so.6 (0x00007fc242fe5000)
	libXext.so.6 => /lib64/libXext.so.6 (0x00007fc242dd3000)
	libGLdispatch.so.0 => /lib64/libGLdispatch.so.0 (0x00007fc242b19000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fc244a9f000)
	libxcb.so.1 => /lib64/libxcb.so.1 (0x00007fc2428f0000)
	libXau.so.6 => /lib64/libXau.so.6 (0x00007fc2426ec000)

Relevant information:

• OS is fedora 28 (4.18.7-200.fc28.x86_64)
• opam2 with latest tgls and tsdl:

$ opam config report
# opam config report
# opam-version      2.0.0 
# self-upgrade      no
# system            arch=x86_64 os=linux os-distribution=fedora os-version=28
# solver            builtin-mccs+glpk
# install-criteria  -removed,-count[version-lag,request],-count[version-lag,changed],-changed
# upgrade-criteria  -removed,-count[version-lag,solution],-new
# jobs              4
# repositories      1 (http) (default repo at 96bb9c7c)
# pinned            0
# current-switch    4.07.0

[eriklovlie]

I'm not a dune/jbuilder expert but this workaround seems to work for now:

(jbuild_version 1)

(executable
 ((name yoyo)
  (ocamlopt_flags (-cclib -lGL))
  (libraries (core_extended tgls.tgl4 tsdl))
  (preprocess (pps (ppx_jane)))
  ))

[dbuenzli]

Normally the libraries are automatically configured using the gl package-config package.

Could you maybe try to give me the output of:

pkg-config --libs gl

and if the package doesn't exist, does it maybe live under a different names (see the output of pkg-config --list-all) ?

[eriklovlie]

It seems this package doesn't exist on fedora 28:

$ pkg-config --list-all | grep -i gl
libglvnd                       libglvnd - Vendor-neutral OpenGL dispatch library vendor interface
xcb-glx                        XCB GLX - XCB GLX Extension
sdl2                           sdl2 - Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer.
egl                            egl - Mesa EGL library
glesv2                         glesv2 - Mesa OpenGL ES 2.0 library
glproto                        GLProto - GL extension headers

[eriklovlie]

Doh! It is in mesa-libGL-devel:

$ dnf repoquery -l mesa-libGL-devel-0:18.0.5-3.fc28.x86_64
Last metadata expiration check: 0:01:02 ago on Mon 17 Sep 2018 07:58:51 PM CEST.
/usr/include/GL/gl.h
/usr/include/GL/gl_mangle.h
/usr/include/GL/glcorearb.h
/usr/include/GL/glext.h
/usr/include/GL/glx.h
/usr/include/GL/glx_mangle.h
/usr/include/GL/glxext.h
/usr/include/GL/internal
/usr/include/GL/internal/dri_interface.h
/usr/lib64/libglapi.so
/usr/lib64/pkgconfig/dri.pc
/usr/lib64/pkgconfig/gl.pc

[eriklovlie]

Things are working after installing mesa-libGL-devel and then reinstalling tgls.

[dbuenzli]

Ah ! Thanks for the info. I guess the package should maybe declare depexts, though formally they are not needed to compile the package.