[bug#49565] [PATCH core-updates] gnu: bootstrap: Use %current-target-system to decide bootstrap path

[Thiago Jung Bauermann via Guix-patches via <guix-patches@gnu.org>]

When cross-building a non-x86 gcc-toolchain on an x86 machine,
‘%current-target’ has the x86 system value and Guix tries to use the
mesboot packages for the bootstrap – which don't work because they’re
currently x86-only.

Therefore look at ‘%current-target-system’ first, which has the non-x86
system value.

* gnu/packages/bootstrap.scm (%bootstrap-inputs): Check
‘%current-target-system’ before ‘%current-system’ to decide whether to use
the mesboot path.
* gnu/packages/commencement.scm (%bootstrap-inputs+toolchain): Ditto.
---
 gnu/packages/bootstrap.scm    | 2 +-
 gnu/packages/commencement.scm | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Hi,

As Maxime Devos mentined previously, glibc-mesboot is only supported on
i686-linux and x86_64-linux and not powerpc64le-linux so it’s strange that
it’s being built on my system. Investigating further, I believe the the
problem is the one described on the commit message above.

With the patch applied on core-updates, I can now get the same error that
the CI is getting when trying to cross-compile a gcc-toolchain package, as
seen here:

https://ci.guix.gnu.org/build/667452/details

But I can’t explain why I see this problem on my machine while it doesn’t
happen on the CI one. Perhaps because I’m running Guix on a foreign distro
(Ubuntu), while the CI presumably uses Guix System?

Here are the derivations that are built now:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build \
	--target=powerpc64le-linux-gnu \
	gcc-toolchain@11
substitute: atualizando substitutos de "https://ci.guix.gnu.org"...  100.0%
substitute: atualizando substitutos de "https://bordeaux.guix.gnu.org"... 100.0%
The following derivations will be built:
   /gnu/store/3smglg4didq9bizfa6mpgr3mwyl025bg-gcc-toolchain-11.1.0.drv
   /gnu/store/bqs0df2b3zalz3f6cs3blx3r13f8agwx-linux-libre-headers-5.10.35.drv
   /gnu/store/adi4bagfjzja2cy0xd4zsjrhrx4l8zzh-gcc-bootstrap-0.drv
   /gnu/store/lw6xvva92vb6yrg5s73c6m507mmg4wpn-gcc-11.1.0.drv
   /gnu/store/qm1lgdvlc6wkch2z6qiglqgfjrc9dl52-binutils-2.36.1.drv
   /gnu/store/23fsjsynp3ryb6npgiipx327ag7dd394-file-boot0-5.39.drv
   /gnu/store/m69xqa8k199gnphplml2pc4qbl0w07pj-make-boot0-4.3.drv
   /gnu/store/35v7glpl1p0sbkmyyls4nlcvfdq80bp4-findutils-boot0-4.8.0.drv
   /gnu/store/3lsjr0fpxx07h7kz42sqqkgqi76wr92w-diffutils-boot0-3.7.drv
   /gnu/store/8v38wv9nd9wa1v0xmb38la68pck43xsr-sed-boot0-4.8.drv
   /gnu/store/dxkjjafij00vda2a515clxq2s75l0pxy-patch-boot0-2.7.6.drv
   /gnu/store/g7zi4asrxwqjy2zskgisw098vs49smhn-tar-boot0-1.34.drv
   /gnu/store/k4p3hhphaw59afaxrhyzc58041736qp9-gawk-boot0-5.1.0.drv
   /gnu/store/qr4hzgwji76cr18c2b4ii10wciyplis3-coreutils-boot0-8.32.drv
   /gnu/store/r16wrs5pfad62pp104m58d6z3r010mq6-glibc-2.33.drv
   /gnu/store/crdznbwd3dq9xrmrxzjk1jl80fb2d1ws-gcc-cross-boot0-10.3.0.drv
   /gnu/store/i337vhnb6gh510s0cprbww1l3qila759-libstdc++-boot0-4.9.4.drv
   /gnu/store/vvkqxj9c4710jajddrqd7qbq1vhy1b2q-bzip2-boot0-1.0.8.drv
   /gnu/store/wry17xmsdh3dg33f4397a609kix5492q-binutils-cross-boot0-2.36.1.drv
   /gnu/store/f2yibv3n2ya2s2hcv2n103bmfb39q0q1-bash-static-5.1.8.drv
   /gnu/store/rn9xwjxjxdr6chwr5bdm0law300120yj-ld-wrapper-boot0-0.drv
   /gnu/store/vnaw38hssdshzsy17vmmy7x7zh3ni7zi-glibc-intermediate-2.33.drv
   /gnu/store/qzhgyd8qnwhy46ajsr1156zap6sryxvf-ld-wrapper-0.drv
   /gnu/store/5g8dn0w3k3m2famxndzxywxl6v3r79cm-libunistring-0.9.10.drv
   /gnu/store/0ycvzp0zmlqac5k3b32a7kb9y5z8sz09-gcc-10.3.0.drv
   /gnu/store/dh10c2zsxyv0i3j43q81xfmkhsnh03sh-libstdc++-10.3.0.drv
   /gnu/store/xwifg8mb9zh0azyxccls9q6gcb56p14h-ld-wrapper-boot3-0.drv
   /gnu/store/yljl3dspmzk6256sdl56swsq2r694nsi-zlib-1.2.11.drv
   /gnu/store/w87mmrp0c5irjmqhjj76m27i39zgj3xf-bash-minimal-5.1.8.drv
   /gnu/store/aag6c2sy2w3xyzs4nm0nfwsqw9c1xkvi-libgc-8.0.4.drv
   /gnu/store/vvljjz5dj38yqfd813z6z6xmwsk32jbg-libatomic-ops-7.6.10.drv
   /gnu/store/k4rzmyxidag567qvf7rkpwl0h041vczm-guile-3.0.7.drv
   /gnu/store/d608rkzh04rlaivcm9y0hsj4icanhdyp-libffi-3.3.drv
   /gnu/store/r16wrs5pfad62pp104m58d6z3r010mq6-glibc-2.33.drv
--8<---------------cut here---------------end--------------->8---


diff --git a/gnu/packages/bootstrap.scm b/gnu/packages/bootstrap.scm
index 5a8028a4652c..b14dc63062e8 100644
--- a/gnu/packages/bootstrap.scm
+++ b/gnu/packages/bootstrap.scm
@@ -927,7 +927,7 @@ exec ~a/bin/.gcc-wrapped -B~a/lib \
 (define (%bootstrap-inputs)
   ;; The initial, pre-built inputs.  From now on, we can start building our
   ;; own packages.
-  (match (%current-system)
+  (match (or (%current-target-system) (%current-system))
     ((or "i686-linux" "x86_64-linux")
      `(("linux-libre-headers" ,%bootstrap-linux-libre-headers)
        ("bootstrap-mescc-tools" ,%bootstrap-mescc-tools)
diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index fb028390a260..2af3dead3c73 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -2396,7 +2396,7 @@ exec " gcc "/bin/" program
 (define (%bootstrap-inputs+toolchain)
   ;; The traditional bootstrap-inputs.  For the i686-linux, x86_64-linux
   ;; Scheme-only bootstrap the actual reduced set with bootstrapped toolchain.
-  (match (%current-system)
+  (match (or (%current-target-system) (%current-system))
     ((or "i686-linux" "x86_64-linux")
      (%boot-mesboot6-inputs))
     (_