4.08 compilation errors

[anmonteiro]

I was trying out the 4.08+beta1 release today and ran into the following errors trying to compile Lwt:

#=== ERROR while compiling lwt.4.1.0 ==========================================#    
# context     2.0.2 | macos/x86_64 | ocaml-variants.4.08.0+beta1 | https://opam.ocaml.org#dc8e74d5
# path        ~/.opam/ocaml-variants.4.08.0+beta1/.opam-switch/build/lwt.4.1.0
# command     ~/.opam/opam-init/hooks/sandbox.sh build jbuilder build -p lwt -j 7                       
# exit-code   1                                              # env-file    ~/.opam/log/lwt-34015-1872ec.env                           # output-file ~/.opam/log/lwt-34015-1872ec.out
### output ###                          
# [...]                                                           
# 208 |   Array1.map_file fd ?pos char c_layout shared size       
#         ^^^^^^^^^^^^^^^                                  
# Error: Unbound value Array1.map_file  
#     ocamlopt src/unix/.lwt_unix.objs/lwt_throttle.{cmx,o}
# File "src/unix/lwt_throttle.ml", line 85, characters 38-55:
# 85 |              Printexc.print_backtrace Pervasives.stderr;
#                                            ^^^^^^^^^^^^^^^^^                   
# Alert deprecated: module Stdlib.Pervasives  
# Use Stdlib instead.                                                            
#                                                                       
# If you need to stay compatible with OCaml < 4.07, you can use the
# stdlib-shims library: https://github.com/ocaml/stdlib-shims           

[anmonteiro]

This failure is related to ocaml/ocaml#1685, so it might just be a matter of depending on the bigarray lib to keep compat with OCaml < 4.06.

[aantron]

The current status is:

• We already depend on bigarray. I opened bigarray compatibility library not linked ocaml/dune#1845 about why that is not working.
• I fixed some new warnings. See the attached commit.
• The PPX and Lwt development depend on ocaml-migrate-parsetree, which needs to be updated. See Start supporting 4.08 / trunk ocaml-ppx/ocaml-migrate-parsetree#50.
• Lwt_react indirectly depends on Ocamlbuild, which needs to be released. See New release for 4.08 ocaml/ocamlbuild#294.
• I opened Travis: test on 4.08.0+beta1 #661 to track testing on 4.08 in Travis, which is blocked on these issues.

[aantron]

The Bigarray issue is now tracked in ocaml/ocaml#2256.

[aantron]

We'll fix the Bigarray issue using conditional compilation. Still waiting on OMP.

[aantron]

The fix for the Bigarray issue now depends on a release of mirage/mmap.

[aantron]

The Bigarray issue is now resolved by the new mmap compatibility package. See the commit linked above.

At this point, it's possible to release the main package lwt, which I will do soon (#675). It's the only package that needs to be updated for 4.08, anyway.

lwt_ppx is still not working on 4.08 due to ocaml-migrate-parsetree not being available.

Lwt development on 4.08 is also still annoying, due to Makefile targets automatically testing lwt_ppx, and due to Lwt's dune files depending on bisect_ppx. We can untangle all this, but I prefer to keep waiting for an ocaml-migrate-parsetree release for now.

[aantron]

Lwt 4.2.0 is compatible with 4.08 and is now installable from opam, so I'm closing this issue. Thanks for reporting!

The PPX and Lwt development still don't work on 4.08, but this is tracked in ocaml-ppx/ocaml-migrate-parsetree#50.

[aantron]

Development on 4.08 now blocked on ppx_tools_versioned:

• Fix compilation warnings related to Migrate_parsetree ocaml-ppx/ppx_tools_versioned#12
• Unbound value Location.print_error on 4.08 ocaml-ppx/ppx_tools_versioned#17