Hello,

The "diff" executable from diffutils stores a reference to the native,
canonical "pr" from coreutils. This is bad for two reasons:

* It makes the Guix System closure bigger by dragging the canonical
  coreutils.

* The cross-compiled diffutils drags the native coreutils to its
  closure, see:

--8<---------------cut here---------------start------------->8---
mathieu@cervin:~$ guix size /gnu/store/5bj91pfnm3z6qbpbl0hp07w12arzk93k-diffutils-3.7
store item                                                       total    self
/gnu/store/j48jp74s1j2mrh7nckg9asdyjv1hvi21-glibc-cross-aarch64-linux-gnu-2.31   158.9    71.4  34.8%
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31              38.4 36.7  17.9%
/gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib           71.0    32.6  15.9%
/gnu/store/xw23yv6fv0cb6n0sbc552l1mkc15yq3n-gcc-cross-aarch64-linux-gnu-7.5.0-lib   186.8    27.9  13.6%
/gnu/store/57xj5gcy1jbl9ai2lnrqnpr0dald9i65-coreutils-8.32          88.0    17.0   8.3%
/gnu/store/sl883skd8gbzcj4fl44w7dv1a5yaa3k4-gcc-cross-sans-libc-aarch64-linux-gnu-7.5.0-lib    80.8     9.8   4.8%
/gnu/store/66m8j38495zdcy2iv55m5d1hj3pxayff-linux-libre-headers-cross-aarch64-linux-gnu-5.4.20     5.1     5.1   2.5%
/gnu/store/bcjcd97xvh0qkvq1maqj6qab88xb30dv-bash-static-5.0.16       1.6     1.6   0.8%
/gnu/store/mmhimfwmmidf09jw1plw3aw1g1zn2nkh-bash-static-5.0.16       1.6     1.6   0.8%
--8<---------------cut here---------------end--------------->8---

The native version of glibc, gcc-lib, coreutils and bash-static are part
of the closure of the cross-compiled coreutils.

I hoped to fix it with the naive patch attached, but it fails for
obscure reasons while building acl:

--8<---------------cut here---------------start------------->8---
FAIL: test/malformed-restore
============================

[4] $ cp "/tmp/guix-build-acl-2.2.53.drv-0/acl-2.2.53/test/malformed-restore-double-owner.acl" tmp.acl -- ok
[5] $ sed -i "s/USER/30001/g" tmp.acl -- failed
ERROR: ld.so: object '/tmp/guix-build-acl-2.2.53.drv-0/acl-2.2.53/.libs/libtestlookup.so' from LD_PRELOAD cannot be preloaded: ignored. != ~
[6] $ sed -i "s/GROUP/30000/g" tmp.acl -- failed
ERROR: ld.so: object '/tmp/guix-build-acl-2.2.53.drv-0/acl-2.2.53/.libs/libtestlookup.so' from LD_PRELOAD cannot be preloaded: ignored. != ~
--8<---------------cut here---------------end--------------->8---

Any idea, what's going on?

Thanks,

Mathieu