Re: Why are these derivations different?

[Jack Hill <jackhill@jackhill.us>]

On Sat, 8 Jun 2019, Marius Bakke wrote:

> Jack Hill <jackhill@jackhill.us> writes:
>
>> Hi Guix,
>>
>> I'm trying to copy the store items for ungoogled-chromium from one of my
>> hosts that has many computational resources to another one that does not,
>> so that I do not have to build ungoogled-chromium on the less powerful
>> host.
>>
>> However, even after copying the store items using guix archive --export |
>> guix archive --import, the less powerful host wants to build
>> ungoogled-chromium because the derivations differ (see attachments).
>
> I suspect this has to do with grafts.  Guix is missing a substitute for
> the 'ungrafted' package and fails to realize the grafted derivation.
>
> Exporting with --no-grafts should do the trick.

Marius,

Thanks! That was it.

If you don't mind, I have a few follow up question to help me understand 
how everything works:

How is guix archive --no-grafts different from guix build --no-grafts? Oh, 
or after reading the manual for --no-grafts again, maybe I used the wrong 
incantation (guix build --no-grafts package-name instead of guix build 
package-name --no-grafts)?

What's really going on with --no-grafts. Is it that guix on my less 
powerful host has never seen the the ungoogled-chromium version build 
against the older dependencies, so doesn't accept the older version that 
could be grafted? I guess, I'm not sure exactly what you mean by "fails to 
realize the grafted derivation". Is that a bug?

Sorry, I don't think that question was very clear. It probably means that 
while I think I know what grafts are, I don't know enough about what's 
going on to ask the question properly. I think this all could be summarized 
as, "please explain more."

Many thanks,
Jack