`Domainslib.0.4.1` build failure with `OCaml 5.0.0+trunk`

[shakthimaan]

Sandmark 5.0.0+trunk (commit 1e52236624bad1c80b3c46857723a35c43974297) fails to build Domainslib.0.4.1 with the following error message:

#=== ERROR while compiling domainslib.0.4.1 ===================================#
# context              2.0.10 | linux/x86_64 | ocaml-base-compiler.5.0.0+trunk | file:///drone/src/dependencies
# path                 /drone/src/_opam/5.0.0+trunk/.opam-switch/build/domainslib.0.4.1
# command              /drone/src/_opam/5.0.0+trunk/bin/dune build -p domainslib -j 47
# exit-code            1
# env-file             /drone/src/_opam/log/domainslib-14015-096783.env
# output-file          /drone/src/_opam/log/domainslib-14015-096783.out
### output ###
#       ocamlc lib/.domainslib.objs/byte/domainslib__Task.{cmo,cmt} (exit 2)
# (cd _build/default && /drone/src/_opam/5.0.0+trunk/bin/ocamlc.opt -w -40 -g -bin-annot -I lib/.domainslib.objs/byte -intf-suffix .ml -no-alias-deps -open Domainslib__ -o lib/.domainslib.objs/byte/domainslib__Task.cmo -c -impl lib/task.ml)
# File "lib/task.ml", line 27, characters 7-10:
# 27 | type _ eff += Wait : 'a promise * task_chan -> 'a eff
#             ^^^
# Error: Unbound type constructor eff
#     ocamlopt lib/.domainslib.objs/native/domainslib__Task.{cmx,o} (exit 2)
# (cd _build/default && /drone/src/_opam/5.0.0+trunk/bin/ocamlopt.opt -w -40 -g -I lib/.domainslib.objs/byte -I lib/.domainslib.objs/native -intf-suffix .ml -no-alias-deps -open Domainslib__ -o lib/.domainslib.objs/native/domainslib__Task.cmx -c -impl lib/task.ml)
# File "lib/task.ml", line 27, characters 7-10:
# 27 | type _ eff += Wait : 'a promise * task_chan -> 'a eff
#             ^^^
# Error: Unbound type constructor eff

What is the recommend fix for the same?

[Sudha247]

Thanks for the report! A fix is here https://github.com/ocaml-multicore/domainslib/pull/65, will make a new release soon.

[Sudha247]

domainslib.0.4.2 works with 5.0.0+trunk. Closing this issue.