bug#39941: Disk-image size increase on core-updates.

[Mathieu Othacehe <m.othacehe@gmail.com>]

Hey,

> Could you find out (perhaps by looking at ‘guix graph -t references’)
> what is referencing these two cross-compilers?

Turns out on master,

--8<---------------cut here---------------start------------->8---
guix size `guix build guile|grep -v debug`
--8<---------------cut here---------------end--------------->8---

returns ~124 MiB, while,

--8<---------------cut here---------------start------------->8---
guix size `guix build --target=aarch64-linux-gnu guile|grep -v debug`
--8<---------------cut here---------------end--------------->8---

returns ~523 MiB.

When building the native guile, only the "lib" output of gcc is
kept. When cross-compiling, the whole cross-compiler is dragged down (as
there's only "out" defined for cross-gcc).

That does not explain the sudden increase, but this is still quite
unfortunate :p

Thanks,

Mathieu