Compilation in OCaml 4.04.1

[maroneze]

I tried compiling landmarks on the freshly-released OCaml 4.04.1, but I got the following error when trying opam install landmarks (I made a local opam repository using the extracted contents of the OCaml release archive):

[ERROR] The compilation of landmarks failed at "make".
Processing  1/1: [landmarks: ocamlfind remove]
#=== ERROR while installing landmarks.1.1 =====================================#
# opam-version 1.2.2
# os           linux
# command      make
# path         /home/andr/.opam/4.04.1+local-git-/build/landmarks.1.1
# compiler     4.04.1+local-git-
# exit-code    2
# env-file     /home/andr/.opam/4.04.1+local-git-/build/landmarks.1.1/landmarks-21719-5f1023.env
# stdout-file  /home/andr/.opam/4.04.1+local-git-/build/landmarks.1.1/landmarks-21719-5f1023.out
# stderr-file  /home/andr/.opam/4.04.1+local-git-/build/landmarks.1.1/landmarks-21719-5f1023.err
### stdout ###
# ocamldep -I . *.mli *.ml > .depend
# ocamlopt  -c clock.c
# ocamlc -w +A-30-42-41-48-40-4 -safe-string -strict-sequence -bin-annot -g -c landmark_misc.ml
# ocamlc -w +A-30-42-41-48-40-4 -safe-string -strict-sequence -bin-annot -g -c landmark_graph.mli
# ocamlc -w +A-30-42-41-48-40-4 -safe-string -strict-sequence -bin-annot -g -c landmark_graph.ml
# ocamlc -w +A-30-42-41-48-40-4 -safe-string -strict-sequence -bin-annot -g -c landmark.mli
# ocamlc -w +A-30-42-41-48-40-4 -safe-string -strict-sequence -bin-annot -g -c landmark.ml
# ocamlmklib -o landmarks clock.o landmark_misc.cmo landmark_graph.cmo landmark.cmo
### stderr ###
# /usr/bin/ld: clock.o: relocation R_X86_64_PC32 against undefined symbol `caml_copy_int64' can not be used when making a shared object; recompile with -fPIC
# /usr/bin/ld: final link failed: Bad value
# collect2: error: ld returned 1 exit status
# make[1]: *** [Makefile:38: landmarks.cma] Error 2
# make: *** [Makefile:15: landmarks] Error 2

I don't have the time right now to try adding the suggested flag, but I'll do later. In any case, I wanted to notify about it.

I am using a Fedora 26-alpha with GCC 7, so it is not impossible that it is an issue due to this somewhat bleeding-edge configuration. However, I am able to compile landmarks on OCaml 4.04.0 without issues.

[maroneze]

Ok, I finally had a look at it and the problem was that my GCC was suffixed with the version number (gcc-7), so the Makefile didn't include the -fPIC flag. Renaming it to gcc avoids the issue.

To make it work in such cases, instead of firstword, the Makefile would have to include something as findstring, but then it could have false positives. So, in the end, I think it's not worth changing anything.

In the unlikely event someone might have a similar issue, they will probably end up finding this, and finding out about the solution.