guix build: Warn when attempting to build an unsupported package.

Fixes <https://issues.guix.gnu.org/51801>.
Reported by Maxim Cournoyer <maxim.cournoyer@gmail.com>.

* guix/scripts/build.scm (options->derivations)[warn-if-unsupported]:
New procedure.
[compute-derivation]: Use it.
* tests/guix-build.sh: Add test.

1 files changed, 11 insertions, 1 deletions

diff --git a/tests/guix-build.sh b/tests/guix-build.sh
index 86e41e2927b..9cbf8fe26d8 100644
--- a/tests/guix-build.sh
+++ b/tests/guix-build.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2012, 2013, 2014, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2012-2014, 2016-2022 Ludovic Courtès <ludo@gnu.org>
 # Copyright © 2020 Marius Bakke <mbakke@fastmail.com>
 # Copyright © 2021 Chris Marusich <cmmarusich@gmail.com>
 #
@@ -31,6 +31,16 @@ guix build --version
 guix build -e '(@ (gnu packages bootstrap) %bootstrap-glibc)' -S
 test "`guix build -e '(@ (gnu packages bootstrap) %bootstrap-glibc)' -S`" = ""
 
+# Warn when attempting to build an unsupported package.
+case "$(guix build intelmetool -s armhf-linux -v0 -n 2>&1)" in
+    *warning:*intelmetool*support*armhf*)
+        true
+        break;;
+    *)
+        false;
+        break;;
+esac
+
 # Should pass.
 guix build -e '(@@ (gnu packages bootstrap) %bootstrap-guile)' |        \
     grep -e '-guile-'