bug#43721: Package 'dune' (ocaml) is not Reproducible

[Julien Lepiller]

Le Wed, 30 Sep 2020 13:56:21 +0200,
zimoun <zimon.toutoune@gmail.com> a écrit :

> Dear,
> 
> Using Guix 04a459a, the classical:
> 
>    guix build dune
>    guix build dune --no-grafts --check -K
> 
> return:
> 
> --8<---------------cut here---------------start------------->8---
> guix build: error: derivation
> `/gnu/store/kg7mnb1b09n5zddgvc4hs8ira3i4jzz2-dune-1.11.3.drv' may not
> be deterministic: output
> `/gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3' differs
> from ‘/gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check’
> --8<---------------cut here---------------end--------------->8---
> 
> then:
> 
>    diff -r --no-dereference
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3{,-check} 
> returns a large output (truncated here):
> 
> --8<---------------cut here---------------start------------->8---
> Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/configurator/configurator.cma
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/configurator/configurator.cma
> differ Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/configurator/configurator__Extract_obj.cmt
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/configurator/configurator__Extract_obj.cmt
> differ Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/configurator/configurator__V1.cmti
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/configurator/configurator__V1.cmti
> differ
> 
> [...]
> 
> Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/_stdune/stdune__User_error.cmti
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/_stdune/stdune__User_error.cmti
> differ Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/_stdune/stdune__User_message.cmti
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/_stdune/stdune__User_message.cmti
> differ Binary files
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3/lib/ocaml/site-lib/dune/_stdune/stdune__User_warning.cmti
> and
> /gnu/store/1wwdmzcjhrpal92sz2zwzhyqmbc3w7ri-dune-1.11.3-check/lib/ocaml/site-lib/dune/_stdune/stdune__User_warning.cmti
> differ --8<---------------cut
> here---------------end--------------->8---
> 
> 
> Is it expected?  Does it comes from timestamp?  Is it avoidable?
> 
> 
> I have not tried (yet) with the patch [1] updating ’dune’.
> 
> [1] <http://issues.guix.gnu.org/issue/40091>
> 
> All the best,
> simon
> 
> 
> 

The difference seems to be bigger than a simple timestamp, but it's all
on binary files, and diffoscope is not very useful for that. Maybe file
system ordering? I'm investigating.