Bring back dune.1.0.0 compatibility

[kit-ty-kate]

We're seeing failures on libraries when using dune 1.x. Notably in dune-release.1.2.0:

#=== ERROR while compiling dune-release.1.2.0 =================================#
# context              2.1.0~beta4 | linux/x86_64 | ocaml-base-compiler.4.11.1 | file:///home/opam/opam-repository
# path                 ~/.opam/4.11.1/.opam-switch/build/dune-release.1.2.0
# command              ~/.opam/4.11.1/bin/dune build -p dune-release -j 55
# exit-code            1
# env-file             ~/.opam/log/dune-release-7-420871.env
# output-file          ~/.opam/log/dune-release-7-420871.out
### output ###
#     ocamlopt bin/main.exe (exit 2)
# (cd _build/default && /home/opam/.opam/4.11.1/bin/ocamlopt.opt -w -40 -g -o bin/main.exe -I /home/opam/.opam/4.11.1/lib/astring -I /home/opam/.opam/4.11.1/lib/bos -I /home/opam/.opam/4.11.1/lib/cmdliner -I /home/opam/.opam/4.11.1/lib/fmt -I /home/opam/.opam/4.11.1/lib/fpath -I /home/opam/.opam/4.11.1/lib/logs -I /home/opam/.opam/4.11.1/lib/ocamlgraph -I /home/opam/.opam/4.11.1/lib/opam-core -I /home/opam/.opam/4.11.1/lib/opam-file-format -I /home/opam/.opam/4.11.1/lib/opam-format -I /home/opam/.opam/4.11.1/lib/opam-repository -I /home/opam/.opam/4.11.1/lib/opam-state -I /home/opam/.opam/4.11.1/lib/re -I /home/opam/.opam/4.11.1/lib/result -I /home/opam/.opam/4.11.1/lib/rresult -I /home/opam/.opam/4.11.1/lib/seq -I /home/opam/.opam/4.11.1/lib/stdlib-shims -I lib /home/opam/.opam/4.11.1/lib/stdlib-shims/stdlib_shims.cmxa /home/opam/.opam/4.11.1/lib/fmt/fmt.cmxa /home/opam/.opam/4.11.1/lib/result/result.cmxa /home/opam/.opam/4.11.1/lib/rresult/rresult.cmxa /home/opam/.opam/4.11.1/lib/astring/astring.cmxa /home/opam/.opam/4.11.1/lib/fpath/fpath.cmxa /home/opam/.opam/4.11.1/lib/ocaml/unix.cmxa /home/opam/.opam/4.11.1/lib/logs/logs.cmxa /home/opam/.opam/4.11.1/lib/bos/bos.cmxa /home/opam/.opam/4.11.1/lib/ocaml/bigarray.cmxa /home/opam/.opam/4.11.1/lib/ocamlgraph/graph.cmxa /home/opam/.opam/4.11.1/lib/re/re.cmxa /home/opam/.opam/4.11.1/lib/opam-core/opam_core.cmxa /home/opam/.opam/4.11.1/lib/opam-file-format/opam-file-format.cmxa /home/opam/.opam/4.11.1/lib/opam-format/opam_format.cmxa /home/opam/.opam/4.11.1/lib/fmt/fmt_tty.cmxa /home/opam/.opam/4.11.1/lib/logs/logs_fmt.cmxa /home/opam/.opam/4.11.1/lib/bos/bos_setup.cmxa lib/dune_release.cmxa /home/opam/.opam/4.11.1/lib/opam-repository/opam_repository.cmxa /home/opam/.opam/4.11.1/lib/opam-state/opam_state.cmxa /home/opam/.opam/4.11.1/lib/cmdliner/cmdliner.cmxa /home/opam/.opam/4.11.1/lib/logs/logs_cli.cmxa /home/opam/.opam/4.11.1/lib/fmt/fmt_cli.cmxa bin/.main.eobjs/cli.cmx bin/.main.eobjs/bistro.cmx bin/.main.eobjs/distrib.cmx bin/.main.eobjs/help.cmx bin/.main.eobjs/lint.cmx bin/.main.eobjs/opam.cmx bin/.main.eobjs/publish.cmx bin/.main.eobjs/tag.cmx bin/.main.eobjs/main.cmx)
# File "_none_", line 1:
# Error: No implementations provided for the following modules:
#          OpamParserTypes referenced from /home/opam/.opam/4.11.1/lib/opam-file-format/opam-file-format.cmxa(OpamParser)

It fails with dune.1.6.2 and 1.9.3 but not with dune 2.0 (since it recompiles with dune itself)

This brings back the dune 1.0 compatibility so that everytime a package tried to compile opam-file-format using dune, opam-file-format itself will be compiled using dune.
Currently the non-dune builds seems to not install the interface-only module: OpamParserTypes and dune doesn't seem to like that.

[dra27]

The linker error is because of the new module FullPos - so OpamParserTypes is not actually an mli-only module. We get away with it in the dune build because it compiles opamParser.ml with -no-alias-deps.

I think it should be consequence-free simply to rename opamParserTypes.mli to opamParserTypes.ml (and obviously update src/dune) since any users will be linking to the .cma/.cmxa and won't notice the change.

[dra27]

Simplification possible to have sample-opam but use it by the current name internally.

[dra27]

Ah, I have just looked at this again in the context of #36 and also realise that this reverts a change in #31. In #23, I added dune as a general depopt but in #31 @rjbou tightened that to 2.0.0. There's no comment there - can you remember why that was, Raja? I'm wondering if it's because only Dune 2 and greater generate dune-package files, so we didn't need to recompile for older Dunes?

This isn't strictly speaking "bringing back" Dune 1.0 compatibility, it's wallpapering over the fault in the make-based build system.

[dra27]

Or at least, to clarify, the changes to the opam file aren't restoring compatibility for Dune 1.x - the changes to tests/sample.opam do!

[rjbou]

At the beginning, dune was restricted to > 1.11.4, which is the same than restricting to > 2.0.0 (as 2.0 is not available).
I should have commented why the restriction, what I remember is that I've tested with several dune version, and the good ones were > 1.11.4 (because of sample? because of package in the test dune file? because of something else that also has been fixed is the meanwhile?).
The restriction is no more needed now, it's compiling & testing correctly.

[dra27]

Thanks, @rjbou - I wonder if it was the test, in that case! In which case, let's merge this and I'll separately work on the problem with the Makefile version.

[dra27]

Thanks, @kit-ty-kate!

[rjbou]

Thanks @kit-ty-kate & @dra27!