Re: How to debug / investigate non-reproducible build for r-repr?

[zimoun]

Dear,

To complement what Brice said.

On Mon, 29 Jun 2020 at 09:13, Brice Waegeneire <brice@waegenei.re> wrote:

> --8<---------------cut here---------------start------------->8---
> $ guix build r-repr --check --keep-failed
> …
> guix build: error: derivation 
> `/gnu/store/5rbf3kb0s96m1nij5s631j1k3mnh75lg-r-repr-1.1.0.drv' may not 
> be deterministic: output 
> `/gnu/store/aah5bpxg1h3sf09ca1plp4cbj745n95y-r-repr-1.1.0' differs from 
> ‘/gnu/store/aah5bpxg1h3sf09ca1plp4cbj745n95y-r-repr-1.1.0-check’
> --8<---------------cut here---------------end--------------->8---

Before going to "diffoscope", personally I try to identify which files
are offending, something like:

--8<---------------cut here---------------start------------->8---
diff -r --no-dereference 
/gnu/store/75xc2l38ml4mz7w2cb4qhg08vs34xr3i-r-repr-1.1.0{,-check}
Binary files 
/gnu/store/75xc2l38ml4mz7w2cb4qhg08vs34xr3i-r-repr-1.1.0/site-library/repr/R/repr.rdb
 and 
/gnu/store/75xc2l38ml4mz7w2cb4qhg08vs34xr3i-r-repr-1.1.0-check/site-library/repr/R/repr.rdb
 differ
Binary files 
/gnu/store/75xc2l38ml4mz7w2cb4qhg08vs34xr3i-r-repr-1.1.0/site-library/repr/R/repr.rdx
 and 
/gnu/store/75xc2l38ml4mz7w2cb4qhg08vs34xr3i-r-repr-1.1.0-check/site-library/repr/R/repr.rdx
 differ
--8<---------------cut here---------------end--------------->8---

Well, you need to check the files "repr/R/repr.{rdb,rdx}".  Because of
the option "--keep-failed", you can go to
"/tmp/guix-build-r-repr-1.1.0.drv-0" and give a look to how these files
are produced.  The classical source of non-determinism is date.  Then if
everything appears to you as expected, then you can go to "diffoscope".


Hope that helps,
simon