bug#30820: Chunked store references in compiled code break grafting (again)

[Ludovic Courtès]

Hello Guix,

The recently added glibc grafts triggered issues that, in the end, show
the return of <http://bugs.gnu.org/24703> (“Store references in 8-byte
chunks in compiled code”).

Specifically on commit 2b5c5f03c2f0a84f84a5517e2e6f5fa9f276ffa5:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build -e '((@ (guix packages) package-replacement) (@@ 
(gnu packages commencement) glibc-final))' --no-grafts
/gnu/store/m07pz38dvizwx2bl9aik6wcbbqbhz6j6-glibc-2.26.105-g0890d5379c-debug
/gnu/store/4sqaib7c2dfjv62ivrg9b8wa7bh226la-glibc-2.26.105-g0890d5379c
/gnu/store/m8m005z2jbvqrj3s5b052camzk2qxpz5-glibc-2.26.105-g0890d5379c-static
$ ./pre-inst-env guix build -e '((@ (guix packages) package-replacement) (@@ 
(gnu packages commencement) glibc-final))' 
/gnu/store/bdgcd723b8l1h8cg8wx4vjfypip29dsn-glibc-2.26.105-g0890d5379c-debug
/gnu/store/l2wzs674z5ac5ccrvp73gdqw02mmzr22-glibc-2.26.105-g0890d5379c
/gnu/store/2rp8zmymxi32wrw4s44f2dc67ci9kxgs-glibc-2.26.105-g0890d5379c-static
$ grep -r 4sqai 
/gnu/store/l2wzs674z5ac5ccrvp73gdqw02mmzr22-glibc-2.26.105-g0890d5379c
Duuma dosiero 
/gnu/store/l2wzs674z5ac5ccrvp73gdqw02mmzr22-glibc-2.26.105-g0890d5379c/sbin/sln 
kongruas
Duuma dosiero 
/gnu/store/l2wzs674z5ac5ccrvp73gdqw02mmzr22-glibc-2.26.105-g0890d5379c/sbin/nscd
 kongruas
--8<---------------cut here---------------end--------------->8---

If we look with hexl-mode, we see that libc-2.26.so contains some of
these too:

--8<---------------cut here---------------start------------->8---
000236a0: b92f 676e 752f 7374 6f48 8d50 01c6 003a  ./gnu/stoH.P...:
000236b0: 4889 4801 48b8 7265 2f34 7371 6169 31f6  H.H.H.re/4sqai1.
000236c0: 4889 4208 48b8 6237 6332 6466 6a76 31ff  H.B.H.b7c2dfjv1.
000236d0: 4889 4210 48b8 3632 6976 7267 3962 c642  H.B.H.62ivrg9b.B
000236e0: 5000 4889 4218 48b8 3877 6137 6268 3232  P.H.B.H.8wa7bh22
000236f0: 4889 4220 48b8 366c 612d 676c 6962 4889  H.B H.6la-glibH.
00023700: 4228 48b8 632d 322e 3236 2e31 4889 4230  B(H.c-2.26.1H.B0
00023710: 48b8 3035 2d67 3038 3930 4889 4238 48b8  H.05-g0890H.B8H.
00023720: 6435 3337 3963 2f6c 4889 4240 48b8 6962  d5379c/address@hidden
00023730: 2f67 636f 6e76 4889 4248 e881 f70b 0048  /gconvH.BH.....H
--8<---------------cut here---------------end--------------->8---

That in turns means that gconv-modules won’t be found, and that guile
with crash during startup with “Uncaught exception” (because early on it
fails to convert file names to UTF-8 through iconv).

To be continued…

Ludo’.