'opam install ocamlfind' fails on Cygwin

[yannl35133]

On a fresh Cygwin 64 (Win10) with opam 2.0.4, with default switch OCaml 4.10.0, ocamlfind cannot be installed.
This is certainly linked to #11453 as it is the same error message.

Their proposed solution, installing ocaml-compiler-libs, worked for me. Maybe you could edit the error message to mention this dependency (or add it as a dependency for opam in Cygwin) ?

See the console :

Me@My-PC ~
$ opam --version
2.0.4


Me@My-PC ~
$ opam switch
#  switch   compiler             description
→  default  ocaml-system.4.10.0  default


Me@My-PC ~
$ opam install ocamlfind
The following actions will be performed:
  ∗ install ocamlfind 1.8.1

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ocamlfind.1.8.1] found in cache

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The compilation of ocamlfind failed at "/usr/bin/make all".

#=== ERROR while compiling ocamlfind.1.8.1 ====================================#
# context     2.0.4 | cygwin/x86_64 | ocaml-system.4.10.0 | https://opam.ocaml.org#513d3767
# path        ~/.opam/default/.opam-switch/build/ocamlfind.1.8.1
# command     /usr/bin/make all
# exit-code   2
# env-file    ~/.opam/log/ocamlfind-6417-c61e7b.env
# output-file ~/.opam/log/ocamlfind-6417-c61e7b.out
### output ###
# [...]
# Use Bytes.create instead.
# ocamlc -I +compiler-libs  -o ocamlfind.exe -g findlib.cma unix.cma \
#            ocaml_args.cmo frontend.cmo
# ocamlc -I +compiler-libs -opaque -c topfind.mli
# ocamlc -I +compiler-libs -opaque -g -c topfind.ml
# File "topfind.ml", line 55, characters 12-41:
# 55 |   let ph = !Toploop.parse_toplevel_phrase l in
#                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Error: Unbound module Toploop
# make[1]: *** [Makefile:165 : topfind.cmo] Erreur 2
# make[1] : on quitte le répertoire « /home/me/.opam/default/.opam-switch/build/ocamlfind.1.8.1/src/findlib »
# make: *** [Makefile:13 : all] Erreur 2



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build ocamlfind 1.8.1
└─
╶─ No changes have been performed

after I installed ocaml-compiler-libs

Me@My-PC ~
$ opam install ocamlfind
The following actions will be performed:
  ∗ install ocamlfind 1.8.1

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ocamlfind.1.8.1] found in cache

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
∗ installed ocamlfind.1.8.1
Done.

[dra27]

Just FTR, the report is affected by ocaml/opam#3954 so this is in fact opam 2.0.5!

This is a packaging problem on Cygwin - I've sent a message to the Cygwin list asking for a dependency on ocaml-compiler-libs to be added either to the ocaml or opam package in Cygwin to fix this.