accounts: Add default value for the 'home-directory' field of <user-account>.

* gnu/system/accounts.scm (<user-account>)[home-directory]: Mark as
thunked and add a default value.
(default-home-directory): New procedure.
* doc/guix.texi (User Accounts): Remove 'home-directory' from example.
* gnu/system/examples/bare-bones.tmpl: Likewise.
* gnu/system/examples/beaglebone-black.tmpl: Likewise.
* gnu/system/examples/desktop.tmpl: Likewise.
* gnu/system/examples/docker-image.tmpl: Likewise.
* gnu/system/examples/lightweight-desktop.tmpl: Likewise.
* gnu/system/install.scm (installation-os): Likewise.
* gnu/tests.scm (%simple-os): Likewise.
* gnu/tests/install.scm (%minimal-os, %minimal-os-on-vda):
(%separate-home-os, %encrypted-root-os, %btrfs-root-os): Likewise.
* tests/accounts.scm ("allocate-passwd")
("allocate-passwd with previous state"): Likewise.

9 files changed, 18 insertions, 26 deletions

diff --git a/gnu/system/accounts.scm b/gnu/system/accounts.scm
index eb18fb5e43..586cff1842 100644
--- a/gnu/system/accounts.scm
+++ b/gnu/system/accounts.scm
@@ -67,7 +67,8 @@
   (supplementary-groups user-account-supplementary-groups
                         (default '()))            ; list of strings
   (comment        user-account-comment (default ""))
-  (home-directory user-account-home-directory)
+  (home-directory user-account-home-directory (thunked)
+                  (default (default-home-directory this-record)))
   (create-home-directory? user-account-create-home-directory? ;Boolean
                           (default #t))
   (shell          user-account-shell              ; gexp
@@ -84,6 +85,10 @@
   (system?        user-group-system?              ; Boolean
                   (default #f)))
 
+(define (default-home-directory account)
+  "Return the default home directory for ACCOUNT."
+  (string-append "/home/" (user-account-name account)))
+
 (define (sexp->user-group sexp)
   "Take SEXP, a tuple as returned by 'user-group->gexp', and turn it into a
 user-group record."
diff --git a/gnu/system/examples/bare-bones.tmpl b/gnu/system/examples/bare-bones.tmpl
index a88bab034f..4f30a5b756 100644
--- a/gnu/system/examples/bare-bones.tmpl
+++ b/gnu/system/examples/bare-bones.tmpl
@@ -35,8 +35,7 @@
                 ;; and "video" allows the user to play sound
                 ;; and access the webcam.
                 (supplementary-groups '("wheel"
-                                        "audio" "video"))
-                (home-directory "/home/alice"))
+                                        "audio" "video")))
                %base-user-accounts))
 
   ;; Globally-installed packages.
diff --git a/gnu/system/examples/beaglebone-black.tmpl b/gnu/system/examples/beaglebone-black.tmpl
index 11678063b2..def05e807d 100644
--- a/gnu/system/examples/beaglebone-black.tmpl
+++ b/gnu/system/examples/beaglebone-black.tmpl
@@ -38,8 +38,7 @@
                 ;; and "video" allows the user to play sound
                 ;; and access the webcam.
                 (supplementary-groups '("wheel"
-                                        "audio" "video"))
-                (home-directory "/home/alice"))
+                                        "audio" "video")))
                %base-user-accounts))
 
   ;; Globally-installed packages.
diff --git a/gnu/system/examples/desktop.tmpl b/gnu/system/examples/desktop.tmpl
index c59bf92681..bc5cbd6e6b 100644
--- a/gnu/system/examples/desktop.tmpl
+++ b/gnu/system/examples/desktop.tmpl
@@ -42,8 +42,7 @@
                 (comment "Alice's brother")
                 (group "users")
                 (supplementary-groups '("wheel" "netdev"
-                                        "audio" "video"))
-                (home-directory "/home/bob"))
+                                        "audio" "video")))
                %base-user-accounts))
 
   ;; This is where we specify system-wide packages.
diff --git a/gnu/system/examples/docker-image.tmpl b/gnu/system/examples/docker-image.tmpl
index 9690d651c1..ca633cc838 100644
--- a/gnu/system/examples/docker-image.tmpl
+++ b/gnu/system/examples/docker-image.tmpl
@@ -15,8 +15,7 @@
                 (comment "Bob's sister")
                 (group "users")
                 (supplementary-groups '("wheel"
-                                        "audio" "video"))
-                (home-directory "/home/alice"))
+                                        "audio" "video")))
                %base-user-accounts))
 
   ;; Globally-installed packages.
diff --git a/gnu/system/examples/lightweight-desktop.tmpl b/gnu/system/examples/lightweight-desktop.tmpl
index a234badd2b..45d9bf447f 100644
--- a/gnu/system/examples/lightweight-desktop.tmpl
+++ b/gnu/system/examples/lightweight-desktop.tmpl
@@ -35,8 +35,7 @@
                 (comment "Bob's sister")
                 (group "users")
                 (supplementary-groups '("wheel" "netdev"
-                                        "audio" "video"))
-                (home-directory "/home/alice"))
+                                        "audio" "video")))
                %base-user-accounts))
 
   ;; Add a bunch of window managers; we can choose one at
diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index bad318d06b..aad1deb913 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -379,8 +379,7 @@ You have been warned.  Thanks for being so brave.\x1b[0m
                   (group "users")
                   (supplementary-groups '("wheel")) ; allow use of sudo
                   (password "")
-                  (comment "Guest of GNU")
-                  (home-directory "/home/guest"))))
+                  (comment "Guest of GNU"))))
 
     (issue %issue)
     (services %installation-services)
diff --git a/gnu/tests.scm b/gnu/tests.scm
index 9e8eed7d95..0871b4c6f7 100644
--- a/gnu/tests.scm
+++ b/gnu/tests.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2017 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;;
@@ -219,8 +219,7 @@ the system under test."
                   (name "alice")
                   (comment "Bob's sister")
                   (group "users")
-                  (supplementary-groups '("wheel" "audio" "video"))
-                  (home-directory "/home/alice"))
+                  (supplementary-groups '("wheel" "audio" "video")))
                  %base-user-accounts))))
 
 (define-syntax-rule (simple-operating-system user-services ...)
diff --git a/gnu/tests/install.scm b/gnu/tests/install.scm
index 277908cc49..c0debbd840 100644
--- a/gnu/tests/install.scm
+++ b/gnu/tests/install.scm
@@ -74,8 +74,7 @@
                   (name "alice")
                   (comment "Bob's sister")
                   (group "users")
-                  (supplementary-groups '("wheel" "audio" "video"))
-                  (home-directory "/home/alice"))
+                  (supplementary-groups '("wheel" "audio" "video")))
                  %base-user-accounts))
     (services (cons (service marionette-service-type
                              (marionette-configuration
@@ -357,8 +356,7 @@ per %test-installed-os, this test is expensive in terms of CPU and storage.")
                   (name "alice")
                   (comment "Bob's sister")
                   (group "users")
-                  (supplementary-groups '("wheel" "audio" "video"))
-                  (home-directory "/home/alice"))
+                  (supplementary-groups '("wheel" "audio" "video")))
                  %base-user-accounts))
     (services (cons (service marionette-service-type
                              (marionette-configuration
@@ -435,12 +433,10 @@ reboot\n")
                          %base-file-systems))
     (users (cons* (user-account
                    (name "alice")
-                   (group "users")
-                   (home-directory "/home/alice"))
+                   (group "users"))
                   (user-account
                    (name "charlie")
-                   (group "users")
-                   (home-directory "/home/charlie"))
+                   (group "users"))
                   %base-user-accounts))
     (services (cons (service marionette-service-type
                              (marionette-configuration
@@ -655,7 +651,6 @@ by 'mdadm'.")
     (users (cons (user-account
                   (name "charlie")
                   (group "users")
-                  (home-directory "/home/charlie")
                   (supplementary-groups '("wheel" "audio" "video")))
                  %base-user-accounts))
     (services (cons (service marionette-service-type
@@ -776,7 +771,6 @@ build (current-guix) and then store a couple of full system images.")
     (users (cons (user-account
                   (name "charlie")
                   (group "users")
-                  (home-directory "/home/charlie")
                   (supplementary-groups '("wheel" "audio" "video")))
                  %base-user-accounts))
     (services (cons (service marionette-service-type