no longer installs on current Ubuntu/Debian due to outdated PCRE

[siccegge]

Hi!

Trying to install easycrypt on Debian Trixie:

$ opam install --deps-only easycrypt --no-depexts

<><> Synchronising pinned packages ><><><><><><><><><><><><><><><><><><><><><><>
[easycrypt.dev] synchronised (no changes)

The following actions will be performed:
=== install 3 packages
  ∗ conf-libpcre   2     [required by pcre]
  ∗ ocaml-inifiles 1.2   [required by easycrypt]
  ∗ pcre           8.0.5 [required by easycrypt]

Proceed with ∗ 3 installations? [y/n] y

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
⬇ retrieved ocaml-inifiles.1.2  (cached)
⬇ retrieved pcre.8.0.5  (cached)
[ERROR] The compilation of conf-libpcre.2 failed at "pkg-config --print-errors --exists libpcre".

#=== ERROR while compiling conf-libpcre.2 =====================================#
# context     2.3.0 | linux/x86_64 |  | https://opam.ocaml.org#4f8a855dcfdd2b6bde1f9512be0e673f4776dfd5
# path        ~/.opam/easycrypt/.opam-switch/build/conf-libpcre.2
# command     ~/.opam/opam-init/hooks/sandbox.sh build pkg-config --print-errors --exists libpcre
# exit-code   1
# env-file    ~/.opam/log/conf-libpcre-23146-e3eb41.env
# output-file ~/.opam/log/conf-libpcre-23146-e3eb41.out
### output ###
# Package libpcre was not found in the pkg-config search path.
# Perhaps you should add the directory containing `libpcre.pc'
# to the PKG_CONFIG_PATH environment variable
# Package 'libpcre', required by 'virtual:world', not found



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build conf-libpcre 2
└─ 
╶─ No changes have been performed

This should be due to deprecation of the (ancient) libpcre -- replaced by pcre2 -- more discussion at
mmottl/pcre-ocaml#25 -- my understanding is that pcre-ocaml also is barely on life support and the recommendation is to move to ocaml-pcre2

[strub]

Hi. Thanks for reporting the issue. There is an OCaml PCRE2 binding, so this should be an easy fix.

[sofotech]

Is there sight on a timeline when this will be fixed?

[siccegge]

as a workaround I just got pcre from (now) oldstable which seems to not cause any problems (apart from some manual messing with packages)

[fdupress]

We also get a dependency on pcre transitively via ocaml-inifiles. This one has been "complete" (and therefore so unmaintained the opam package goes and fetches the source from an old ubuntu source package) for a while and won't be easy to fix up in the opam repository.

In practice, I got it to compile (but it emits warnings and remains untested) by adding module Pcre = Pcre2 at the start of each relevant source file. But I'm worried that trying to push an update would commit whoever does it to maintainership, and I do not wish this on anybody.

[fdupress]

In practice, I got it to compile (but it emits warnings and remains untested) by adding module Pcre = Pcre2 at the start of each relevant source file. But I'm worried that trying to push an update would commit whoever does it to maintainership, and I do not wish this on anybody.

One easy solution here that commits us only to a limited version of maintainership is to vendor the patched version.
It is licenced under LGPL 2.1 or later. (So we would likely want to ultimately remove the vendored component.)

[strub]

One easy solution here that commits us only to a limited version of maintainership is to vendor the patched version. It is licenced under LGPL 2.1 or later. (So we would likely want to ultimately remove the vendored component.)

We are under the MIT licencese. We can link to LGPL code.