opam install fails (pg_query 0.9.7, arch linux, ocaml 5.1.0, opam 2.3.0)

[jake-miles]

$ opam install pg_query

The following actions will be performed:
=== install 1 package
  ∗ pg_query 0.9.7

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
⬇ retrieved pg_query.0.9.7  (cached)
[ERROR] The compilation of pg_query.0.9.7 failed at "dune build -p pg_query -j 15 @install".

#=== ERROR while compiling pg_query.0.9.7 =====================================#
# context              2.3.0 | linux/x86_64 | ocaml.5.1.0 | https://opam.ocaml.org#cd5853b9a4dc5dfdb5f53cee126a86701c2b2d12
# path                 ~/src/devmap/_opam/.opam-switch/build/pg_query.0.9.7
# command              ~/.opam/opam-init/hooks/sandbox.sh build dune build -p pg_query -j 15 @install
# exit-code            1
# env-file             ~/.opam/log/pg_query-69766-e11519.env
# output-file          ~/.opam/log/pg_query-69766-e11519.out
### output ###
# [...]
# compiling src/postgres/src_port_snprintf.c
# which: no protoc-gen-c in (/home/jmiles/src/devmap/_opam/.opam-switch/build/pg_query.0.9.7/_build/install/default/bin:/home/jmiles/src/devmap/_opam/bin:/home/jmiles/bin:/home/jmiles/.local/gprolog/gprolog-1.6.0/bin/:/home/jmiles/.opam/ocaml.5.1.0/bin:/home/jmiles/.opam/ocaml.5.1.0/bin:/home/jmiles/bin:/home/jmiles/.local/gprolog/gprolog-1.6.0/bin/:/home/jmiles/.opam/ocaml.5.1.0/bin:/home/jmil[...]
# src/postgres/src_port_snprintf.c:374:1: error: conflicting types for ‘strchrnul’; have ‘const char *(const char *, int)’
#   374 | strchrnul(const char *s, int c)
#       | ^~~~~~~~~
# In file included from ./src/postgres/include/c.h:61,
#                  from src/postgres/src_port_snprintf.c:62:
# /usr/include/string.h:286:14: note: previous declaration of ‘strchrnul’ with type ‘char *(const char *, int)’
#   286 | extern char *strchrnul (const char *__s, int __c)
#       |              ^~~~~~~~~
# make: *** [Makefile:140: src/postgres/src_port_snprintf.o] Error 1
                                     



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build pg_query 0.9.7
└─ 
╶─ No changes have been performed

[anmonteiro]

working on a release here ocaml/opam-repository#27216

follow that PR / opam pin add pg_query --dev-repo while it isn't merged.