Add test for bootstrapping Bash

* tests/bash-without-bash.scm: New file.
* Makefile.am (check-bootstrap): New target.

Makefile.am

@@ -40,6 +40,10 @@ test-list: ; @echo $(TESTS)
 check-spec:
 	$(MAKE) $(AM_MAKEFLAGS) -L -C tests/spec check
 
+.PHONY: check-bootstrap
+check-bootstrap:
+	guix build -f tests/bash-without-bash.scm
+
 dist-hook:
 	echo $(VERSION) > $(distdir)/.tarball-version
 

tests/bash-without-bash.scm

@@ -0,0 +1,37 @@
+(use-modules ((gnu packages bash) #:select (bash))
+             (guix build-system)
+             (guix packages)
+             (guix store)
+             (guix utils)
+             (ice-9 match))
+
+(define geesh
+  (load (string-append (current-source-directory) "/../guix.scm")))
+
+(define geesh-with-links
+  (package
+    (inherit geesh)
+    (arguments
+     (substitute-keyword-arguments (package-arguments geesh)
+       ((#:phases phases '%standard-phases)
+        `(modify-phases ,phases
+           (add-after 'install 'link-bash
+             (lambda* (#:key outputs #:allow-other-keys)
+               (let ((out (assoc-ref outputs "out")))
+                 (symlink (string-append out "/bin/geesh")
+                          (string-append out "/bin/sh"))
+                 (symlink (string-append out "/bin/geesh")
+                          (string-append out "/bin/bash")))))))))))
+
+(define bash-without-bash
+  (let ((bash-bag (package->bag bash)))
+    (bag
+      (inherit bash-bag)
+      (build-inputs
+       `(("bash" ,geesh-with-links)
+         ,@(filter (match-lambda
+                     ((name . _)
+                      (not (member name '("bash")))))
+                   (bag-build-inputs bash-bag)))))))
+
+(bag->derivation (open-connection) bash-without-bash)