[bug#50238] [PATCH] build-self: Try printing nicer error messages.

[Ludovic Courtès]

Hi,

Maxime Devos <maximedevos@telenet.be> skribis:

> This patch improves the error message generated by "guix time-machine"
> and presumably "guix pull" as well when the guix derivation fails to
> compute.
>
> Before: something like <https://issues.guix.gnu.org/50232>.
> After: something like
>
> [...]
> substitute: lijst van substitutes van ?[...]? aan het bijwerken... 100.0%
> /gnu/store/4yx3vms0rfpzd1430za3g4pa6jvjsfw9-nowhere.tar.bz2.drv bouwen...
> /error: build of 
> `/gnu/store/6s0cmkfa4hq7d9w8g08mv2rhq0cr7wqc-subversion-1.14.1.drv' failed
> guix time-machine: fout: You found a bug: the program 
> '/gnu/store/j07lizpjf7v65shdgxyxddz171g6vjvx-compute-guix-derivation'
> failed to compute the derivation for Guix (version: 
> "9fc551e089c25f510f918a2c52917ba4e842f1c3"; system: "x86_64-linux";
> host version: "75a3413b4e5c1f7443eb944a36ff364f4c4085f4"; pull-version: 1).
> Please report it by email to <bug-guix@gnu.org

I sympathize with the goal but unsure about the implementation.

To me, compute-guix-derivation should remain as simple as possible and
it shouldn't take care of UI concerns.  Having said that, I don't know
how to address the problem above while sticking to this principle.

WDYT?

Ludo'.