Hello:

the downloaded git archive for camlp4 says it is for
ocaml 4.05.0 and fails to compile on 4.04.0:

raffalli@delli7:~/Caml/patoline$ opam install camlp4
The following actions will be performed:
  ∗  install camlp4 4.04

=-=- Gathering sources =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
[camlp4] git://github.com/ocaml/camlp4#trunk already up-to-date

=-=- Processing actions -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
[ERROR] The compilation of camlp4 failed at "./configure --bindir=/home/raffalli/.opam/4.04.0/bin
        --libdir=/home/raffalli/.opam/4.04.0/lib/ocaml --pkgdir=/home/raffalli/.opam/4.04.0/lib".
	Processing  1/1: [camlp4: rm]
	#=== ERROR while installing camlp4.4.04 =======================================#
	# opam-version 1.2.2
	# os           linux
	# command      ./configure --bindir=/home/raffalli/.opam/4.04.0/bin --libdir=/home/raffalli/.opam/4.04.0/lib/ocaml --pkgdir=/home/raffalli/.opam/4.04.0/lib
	# path         /home/raffalli/.opam/4.04.0/build/camlp4.4.04
	# compiler     4.04.0
	# exit-code    2
	# env-file     /home/raffalli/.opam/4.04.0/build/camlp4.4.04/camlp4-2996-1872ec.env
	# stdout-file  /home/raffalli/.opam/4.04.0/build/camlp4.4.04/camlp4-2996-1872ec.out
	# stderr-file  /home/raffalli/.opam/4.04.0/build/camlp4.4.04/camlp4-2996-1872ec.err
	### stdout ###
	# This version of Camlp4 is for OCaml 4.05 but you are using OCaml 4.04.0.
	# If building Camlp4 directly from git, use the 4.04 branch.



=-=- Error report -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
The following actions failed
  ∗  install camlp4 4.04
  No changes have been performed


Cheers,
Christophe