ui: 'warn-about-load-error' provides hints for unbound variables.

* guix/ui.scm (warn-about-load-error): Add 'unbound-variable' clause.
* tests/guix-build.sh: Add test.

1 files changed, 17 insertions, 2 deletions

diff --git a/tests/guix-build.sh b/tests/guix-build.sh
index d16b92d189..37666ffd01 100644
--- a/tests/guix-build.sh
+++ b/tests/guix-build.sh
@@ -146,8 +146,8 @@ test `guix build -d --sources=transitive foo \
       | wc -l` -eq 3
 
 
-# Unbound variables.
-cat > "$module_dir/foo.scm"<<EOF
+# Unbound variable in thunked field.
+cat > "$module_dir/foo.scm" <<EOF
 (define-module (foo)
   #:use-module (guix tests)
   #:use-module (guix build-system trivial))
@@ -162,6 +162,21 @@ if guix build package-with-something-wrong -n; then false; else true; fi
 guix build package-with-something-wrong -n 2> "$module_dir/err" || true
 grep "unbound" "$module_dir/err"		     # actual error
 grep "forget.*(gnu packages base)" "$module_dir/err" # hint
+
+# Unbound variable at the top level.
+cat > "$module_dir/foo.scm" <<EOF
+(define-module (foo)
+  #:use-module (guix tests))
+
+(define-public foo
+  (dummy-package "package-with-something-wrong"
+    (build-system gnu-build-system)))      ;unbound variable
+EOF
+
+guix build sed -n 2> "$module_dir/err"
+grep "unbound" "$module_dir/err"		     # actual error
+grep "forget.*(guix build-system gnu)" "$module_dir/err" # hint
+
 rm -f "$module_dir"/*
 
 # Wrong 'define-module' clause reported by 'warn-about-load-error'.