Re: Proper use of `guix build X --rounds=2`

[Skyler Ferris <skyvine@protonmail.com>]

On 2/18/24 15:23, Carlo Zancanaro wrote:
> I'm not sure if this is considered a bug or not, but the solution to
> your problem is to use --check. Using your test file running:
>
>    guix build -f test.scm --check
>
> should run the build one time, and compare the output with what is in
> the store. Then:
>
>    guix build -f test.scm --check --rounds=2
>
> should run the build twice, and check against the output that is already
> in the store.

Thanks for clarifying! Now that you've pointed out this distinction, it 
makes sense and shouldn't cause significant problems for me moving forward.

> It's a bit confusing, but --rounds only applies if there is actually a
> build to do, whereas --check forces a build and compares against the
> store.
Yeah, the interface does seem a little confusing. There's probably a 
more intuitive way to present this, but I don't know why the options 
ended up this way to begin them or what the implications of a change 
would be. I do see now that the manual notes in the `--check` section 
that one of the uses is to check that a build is deterministic. I have 
some understanding of `guix challenge`, but only thought about it for 
the purpose of checking whether or not the substitute server is 
providing trustworthy builds not for checking the package itself, so my 
mind didn't go there when thinking about this problem.