support ocaml 4.10. remove usage of -unsafe-string

[olafhering]

[   57s] + /usr/bin/mkdir /home/abuild/rpmbuild/BUILDROOT/unison-2.51.2-60.opt_410.1.x86_64
[   57s] + cd unison-2.51.2
[   57s] + export SUSE_ASNEEDED=0
[   57s] + SUSE_ASNEEDED=0
[   57s] + NATIVE=true
[   57s] + make UISTYLE=gtk2 NATIVE=true THREADS=true
[   57s] UISTYLE = gtk2
[   57s] Building for Unix
[   57s] NATIVE = true
[   57s] THREADS = true
[   57s] STATIC = false
[   57s] OSTYPE = linux
[   57s] OSARCH = Linux
[   57s] ocamlopt: ubase/rx.mli ---> ubase/rx.cmi
[   57s] ocamlopt -g -unsafe-string -I lwt -I ubase -I system -I fsmonitor -I fsmonitor/linux -I fsmonitor/windows -I system/generic -I lwt/generic -I +lablgtk2 -c /home/abuild/rpmbuild/BUILD/unison-2.51.2/ubase/rx.mli
[   58s] ocamlopt: OCaml has been configured with -force-safe-string: -unsafe-string is not available.
```

[glondu]

Note that I am working on a bin_prot-based fork that builds without -unsafe-string:

https://github.com/glondu/unison/tree/bin_prot

The specific commit removing -unsafe-string is:

glondu@100916a

I am waiting for the pull request #315 to be merged to propose a pull request with this commit.

[olafhering]

This branch compiles in native mode, but fails in bytecode (ocaml 4.08+4.09):

[   75s] + /usr/bin/mkdir /home/abuild/rpmbuild/BUILDROOT/unison-2.51.2.87922db-63.obc_408.1.x86_64
[   75s] + cd unison-2.51.2.87922db
[   75s] + export SUSE_ASNEEDED=0
[   75s] + SUSE_ASNEEDED=0
[   75s] + NATIVE=false
[   75s] + make UISTYLE=gtk2 NATIVE=false THREADS=true
[   75s] UISTYLE = gtk2
[   75s] Building for Unix
[   75s] NATIVE = false
[   75s] THREADS = true
[   75s] STATIC = false
[   75s] OSTYPE = linux
[   75s] OSARCH = Linux
[   75s] /usr/bin/ocamlfind ocamlc: ubase/rx.mli ---> ubase/rx.cmi
[   75s] /usr/bin/ocamlfind ocamlc -g -package ppx_bin_prot -I lwt -I ubase -I system -I fsmonitor -I fsmonitor/linux -I fsmonitor/windows -I system/generic -I lwt/generic -I /usr/lib64/ocaml/lablgtk2 -custom -g -c /home/abuild/rpmbuild/BUILD/unison-2.51.2.87922db/ubase/rx.mli
[   76s] File "_none_", line 1:
[   76s] Error: Cannot load ppx_bin_prot: this object file uses unsafe features
[   76s] make: *** [Makefile.OCaml:402: ubase/rx.cmi] Error 2
[   76s] error: Bad exit status from /var/tmp/rpm-tmp.iLlRbM (%build)

[glondu]

Error: Cannot load ppx_bin_prot: this object file uses unsafe features

Oh. But Unison itself already uses unsafe features (the Obj module is used in Proplist). Maybe an option is missing.

Nevertheless, the specific commit I was pointing at (100916a) does not depend on ppx_bin_prot... did you try it?

[olafhering]

I used the entire branch. Will try to use selected commits.

[glondu]

Will try to use selected commits.

I've pushed a branch for your convenience:

https://github.com/glondu/unison/tree/safe-string

[olafhering]

https://github.com/glondu/unison/tree/safe-string

Thanks. This worked for ocaml 4.07 to 4.10. With 4.05 this branch fails:

[   76s] ocamlopt -g -I lwt -I ubase -I system -I fsmonitor -I fsmonitor/linux -I fsmonitor/windows -I system/generic -I lwt/generic -I /usr/lib64/ocaml/lablgtk2 -c /home/abuild/rpmbuild/BUILD/unison-2.51.2.100916a/lwt/generic/lwt_unix_impl.ml
[   76s] File "/home/abuild/rpmbuild/BUILD/unison-2.51.2.100916a/lwt/generic/lwt_unix_impl.ml", line 356, characters 16-33:
[   76s] Error: Unbound module Stdlib
[   76s] make: *** [Makefile.OCaml:412: lwt/generic/lwt_unix_impl.cmx] Error 2

Does it needs its own copy of lwt?

[glondu]

With 4.05 this branch fails:

[   76s] ocamlopt -g -I lwt -I ubase -I system -I fsmonitor -I fsmonitor/linux -I fsmonitor/windows -I system/generic -I lwt/generic -I /usr/lib64/ocaml/lablgtk2 -c /home/abuild/rpmbuild/BUILD/unison-2.51.2.100916a/lwt/generic/lwt_unix_impl.ml
[   76s] File "/home/abuild/rpmbuild/BUILD/unison-2.51.2.100916a/lwt/generic/lwt_unix_impl.ml", line 356, characters 16-33:
[   76s] Error: Unbound module Stdlib
[   76s] make: *** [Makefile.OCaml:412: lwt/generic/lwt_unix_impl.cmx] Error 2

Stdlib was introduced only recently. I guess this could be fixed with stdlib-shims (or by replacing occurrences of Stdlib by Pervasives)... but why bother? I would just declare the minimal supported OCaml version to be 4.08.

Does it needs its own copy of lwt?

Unison predates lwt as a standalone project. lwt has evolved a lot since the epoch it was part of Unison, so I expect some work to adapt Unison to a modern lwt. But who knows, maybe it is trivial... Anyway, this is not my top priority for now (which is to make Unison independent of OCaml's marshalling).

[olafhering]

Well, either way would probably work for me.
Once I upgrade Tumbleweed to 4.10 I will use this branch, or whatever will be available at that time. Thank you for your support.

[glondu]

Note that I've made a pull request for this: #351

[gdt]

I believe fixes are merged and this is resolved in 2.51.3. If not, please open a new PR with rationale for what's wrong in 2.51.3/master, assuming as little reader knowledge as possible.