trunk-support does't build with ocaml-trunk

[hhugo]

#=== ERROR while compiling ocaml-compiler-libs.v0.12.4 ========================#
# context     2.1.0 | linux/x86_64 |  | https://opam.ocaml.org#8f3e6876
# path        ~/.opam/trunk/.opam-switch/build/ocaml-compiler-libs.v0.12.4
# command     ~/.opam/opam-init/hooks/sandbox.sh build dune build -p ocaml-compiler-libs -j 7 @install
# exit-code   1
# env-file    ~/.opam/log/ocaml-compiler-libs-140689-507985.env
# output-file ~/.opam/log/ocaml-compiler-libs-140689-507985.out
### output ###
# (cd _build/default && /home/hugo/.opam/trunk/bin/ocamlopt.opt -w -40 -safe-string -g -I src/read_cma/.read_cma.objs/byte -I src/read_cma/.read_cma.objs/native -I /home/hugo/.opam/trunk/lib/ocaml/compiler-libs -intf-suffix .ml -no-alias-deps -o src/read_cma/.read_cma.objs/native/read_cma.cmx -c -impl src/read_cma/read_cma.ml)
# File "src/read_cma/read_cma.ml", line 15, characters 2-61:
# 15 |   List.map toc.lib_units ~f:(fun cu -> cu.Cmo_format.cu_name)
#        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Error: This expression has type Cmo_format.compunit list
#        but an expression was expected of type StdLabels.String.t list
#        Type Cmo_format.compunit is not compatible with type
#          StdLabels.String.t = string

[tmattio]

Thanks for the report @hhugo. I'm assigning myself but likely won't have time in the next couple of weeks. Would happily review a PR in case you want to give this a go before I do.

[tmattio]

@hhugo are you certain this is an issue with ppxlib? The error report seems to be a build failure on ocaml-compiler-libs

[shym]

I confirm ocaml-compiler-libs do not compile in a switch for trunk, without ppxlib installed (before the upgrade that reproduced the failure).

[hhugo]

The error indeed comes from ocaml-compiler-libs

[pitag-ha]

@hhugo, one question: Have you ended up filing the issue somewhere else?