dune build errors

[OlivierNicole]

I'm trying to use the lin library in a project, but dune build is failing on current main (a7a032f at the time of writing):

File "lib/STM.ml", line 308, characters 23-32:
308 |     Test.make ~retries:rep_count ~count ~name:("parallel " ^ name ^ " (w/shrink retries)")
                             ^^^^^^^^^
Error: The function applied to this argument has type
         ?if_assumptions_fail:[ `Fatal | `Warning ] * float ->
         ?long_factor:int ->
         ?max_gen:int ->
         ?max_fail:int -> ?small:('a -> int) -> QCheck2.Test.t
This argument cannot be applied with label ~retries
File "lib/lin.ml", line 190, characters 30-31:
190 |     Test.make ~count ~retries:3 ~name:("Linearizable " ^ name)
                                    ^
Error: The function applied to this argument has type
         ?if_assumptions_fail:[ `Fatal | `Warning ] * float ->
         ?long_factor:int ->
         ?max_gen:int ->
         ?max_fail:int -> ?small:('a -> int) -> QCheck2.Test.t
This argument cannot be applied with label ~retries
File "/home/olivier/compiler/trunk/_opam/lib/lockfree/dune-package", line 1, characters 11-14:
1 | (lang dune 3.0)
               ^^^
Error: Version 3.0 of the dune language is not supported.
Supported versions of this extension in version 3.0 of the dune language:
- 1.0 to 1.12
- 2.0 to 2.9

I am currently looking for the causes.

[jmid]

With a recent trunk ocaml installed building requires something like the two first steps from the CI:
https://github.com/jmid/multicoretests/blob/483fa6415d2d8c12c92111d6d5218f2457d5667e/.github/workflows/linux-500-workflow.yml#L27-L29

This is not clear from the outside though! To help others it would be nice to write up "Installation instructions" in the README.

The dependencies include

• a number of pin-depends in the opam-file pointing to packages patched for 5.0
• a pin to the QCheck repo - since we use the ~retries feature which has been merged - Add parameter for retrying a property while shrinking c-cube/qcheck#212 but not released yet

IIUC, part of the above error message complains about not knowing about the new ~retries parameter.

[OlivierNicole]

Indeed, opam install . --deps-only allowed me to dune build without errors.

This is not clear from the outside though! To help others it would be nice to write up "Installation instructions" in the README.

Done in #6.