Merge remote-tracking branch 'origin/master' into core-updates

20 files changed, 233 insertions, 129 deletions

diff --git a/guix/build/emacs-build-system.scm b/guix/build/emacs-build-system.scm
index e2b792d3dc..52c1ea177e 100644
--- a/guix/build/emacs-build-system.scm
+++ b/guix/build/emacs-build-system.scm
@@ -76,10 +76,10 @@ archive, a directory, or an Emacs Lisp file."
 (define* (add-source-to-load-path #:key dummy #:allow-other-keys)
   "Augment the EMACSLOADPATH environment variable with the source directory."
   (let* ((source-directory (getcwd))
-         (emacs-load-path-value (string-append (getenv "EMACSLOADPATH") ":"
-                                               source-directory)))
+         (emacs-load-path-value (string-append source-directory ":"
+                                               (getenv "EMACSLOADPATH"))))
     (setenv "EMACSLOADPATH" emacs-load-path-value)
-    (format #t "source directory ~s appended to the `EMACSLOADPATH' \
+    (format #t "source directory ~s prepended to the `EMACSLOADPATH' \
 environment variable\n" source-directory)))
 
 (define* (build #:key outputs inputs #:allow-other-keys)
@@ -239,15 +239,14 @@ second hyphen.  This corresponds to 'name-version' as used in ELPA packages."
     (add-after 'unpack 'add-source-to-load-path add-source-to-load-path)
     (delete 'bootstrap)
     (delete 'configure)
-    ;; Move the build phase after install: the .el files are byte compiled
-    ;; directly in the store.
     (delete 'build)
     (replace 'check check)
     (replace 'install install)
-    (add-after 'install 'build build)
     (add-after 'install 'make-autoloads make-autoloads)
     (add-after 'make-autoloads 'patch-el-files patch-el-files)
-    (add-after 'make-autoloads 'move-doc move-doc)))
+    ;; The .el files are byte compiled directly in the store.
+    (add-after 'patch-el-files 'build build)
+    (add-after 'build 'move-doc move-doc)))
 
 (define* (emacs-build #:key inputs (phases %standard-phases)
                       #:allow-other-keys #:rest args)
diff --git a/guix/build/qt-build-system.scm b/guix/build/qt-build-system.scm
index 46fcad7848..be2b808901 100644
--- a/guix/build/qt-build-system.scm
+++ b/guix/build/qt-build-system.scm
@@ -90,8 +90,8 @@ add a dependency of that output on Qt."
       (unless (member output qt-wrap-excluded-outputs)
         (let ((bin-list     (find-files-to-wrap directory))
               (vars-to-wrap (variables-for-wrapping
-                             (append (list output)
-                                         input-directories))))
+                             (append (list directory)
+                                     input-directories))))
           (when (not (null? vars-to-wrap))
             (for-each (cut apply wrap-program <> vars-to-wrap)
                       bin-list)))))))
diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index ce7999b433..248d6761fc 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2015 David Thompson <davet@gnu.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Guillaume Le Vaillant <glv@posteo.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -43,6 +44,7 @@
             MS_BIND
             MS_MOVE
             MS_STRICTATIME
+            MS_LAZYTIME
             MNT_FORCE
             MNT_DETACH
             MNT_EXPIRE
@@ -451,6 +453,7 @@ the returned procedure is called."
 (define MS_BIND            4096)
 (define MS_MOVE            8192)
 (define MS_STRICTATIME 16777216)
+(define MS_LAZYTIME    33554432)
 
 (define MNT_FORCE       1)
 (define MNT_DETACH      2)
diff --git a/guix/derivations.scm b/guix/derivations.scm
index 6cdf55b1fe..480a65c78b 100644
--- a/guix/derivations.scm
+++ b/guix/derivations.scm
@@ -86,6 +86,7 @@
             fixed-output-derivation?
             offloadable-derivation?
             substitutable-derivation?
+            derivation-input-fold
             substitution-oracle
             derivation-hash
             derivation-properties
@@ -303,6 +304,29 @@ result is the set of prerequisites of DRV not already in valid."
             (derivation-output-path (assoc-ref outputs sub-drv)))
           sub-drvs))))
 
+(define* (derivation-input-fold proc seed inputs
+                                #:key (cut? (const #f)))
+  "Perform a breadth-first traversal of INPUTS, calling PROC on each input
+with the current result, starting from SEED.  Skip recursion on inputs that
+match CUT?."
+  (let loop ((inputs inputs)
+             (result seed)
+             (visited (set)))
+    (match inputs
+      (()
+       result)
+      ((input rest ...)
+       (let ((key (derivation-input-key input)))
+         (cond ((set-contains? visited key)
+                (loop rest result visited))
+               ((cut? input)
+                (loop rest result (set-insert key visited)))
+               (else
+                (let ((drv (derivation-input-derivation input)))
+                  (loop (append (derivation-inputs drv) rest)
+                        (proc input result)
+                        (set-insert key visited))))))))))
+
 (define* (substitution-oracle store inputs-or-drv
                               #:key (mode (build-mode normal)))
   "Return a one-argument procedure that, when passed a store file name,
@@ -322,25 +346,15 @@ substituter many times."
     (cut valid-derivation-input? store <>))
 
   (define (closure inputs)
-    (let loop ((inputs inputs)
-               (closure '())
-               (visited (set)))
-      (match inputs
-        (()
-         (reverse closure))
-        ((input rest ...)
-         (let ((key (derivation-input-key input)))
-           (cond ((set-contains? visited key)
-                  (loop rest closure visited))
-                 ((valid-input? input)
-                  (loop rest closure (set-insert key visited)))
-                 (else
-                  (let ((drv (derivation-input-derivation input)))
-                    (loop (append (derivation-inputs drv) rest)
-                          (if (substitutable-derivation? drv)
-                              (cons input closure)
-                              closure)
-                          (set-insert key visited))))))))))
+    (reverse
+     (derivation-input-fold (lambda (input closure)
+                              (let ((drv (derivation-input-derivation input)))
+                                (if (substitutable-derivation? drv)
+                                    (cons input closure)
+                                    closure)))
+                            '()
+                            inputs
+                            #:cut? valid-input?)))
 
   (let* ((inputs (closure (map (match-lambda
                                  ((? derivation-input? input)
diff --git a/guix/import/cran.scm b/guix/import/cran.scm
index e47aff2b12..d9018cc7da 100644
--- a/guix/import/cran.scm
+++ b/guix/import/cran.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2015, 2016, 2017, 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
-;;; Copyright © 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -505,7 +505,7 @@ s-expression corresponding to that package, or #f on failure."
              ((bioconductor)
               ;; Retry import from CRAN
               (cran->guix-package package-name 'cran))
-             (else #f)))))))
+             (else (values #f '()))))))))
 
 (define* (cran-recursive-import package-name #:optional (repo 'cran))
   (recursive-import package-name repo
diff --git a/guix/import/crate.scm b/guix/import/crate.scm
index 8dc014d232..4c3f8000d0 100644
--- a/guix/import/crate.scm
+++ b/guix/import/crate.scm
@@ -178,21 +178,20 @@ and LICENSE."
          (close-port port)
          pkg))
 
-(define %dual-license-rx
-  ;; Dual licensing is represented by a string such as "MIT OR Apache-2.0".
-  ;; This regexp matches that.
-  (make-regexp "^(.*) OR (.*)$"))
+(define (string->license string)
+  (filter-map (lambda (license)
+                (and (not (string-null? license))
+                     (not (any (lambda (elem) (string=? elem license))
+                               '("AND" "OR" "WITH")))
+                     (or (spdx-string->license license)
+                         'unknown-license!)))
+              (string-split string (string->char-set " /"))))
 
 (define* (crate->guix-package crate-name #:optional version)
   "Fetch the metadata for CRATE-NAME from crates.io, and return the
 `package' s-expression corresponding to that package, or #f on failure.
 When VERSION is specified, attempt to fetch that version; otherwise fetch the
 latest version of CRATE-NAME."
-  (define (string->license string)
-    (match (regexp-exec %dual-license-rx string)
-      (#f (list (spdx-string->license string)))
-      (m  (list (spdx-string->license (match:substring m 1))
-                (spdx-string->license (match:substring m 2))))))
 
   (define (normal-dependency? dependency)
     (eq? (crate-dependency-kind dependency) 'normal))
diff --git a/guix/import/utils.scm b/guix/import/utils.scm
index 4694b6e7ef..47fc8276a9 100644
--- a/guix/import/utils.scm
+++ b/guix/import/utils.scm
@@ -34,15 +34,16 @@
   #:use-module (guix gexp)
   #:use-module (guix store)
   #:use-module (guix download)
+  #:use-module (guix sets)
   #:use-module (gnu packages)
   #:use-module (ice-9 match)
   #:use-module (ice-9 rdelim)
   #:use-module (ice-9 receive)
   #:use-module (ice-9 regex)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-9)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
-  #:use-module (srfi srfi-41)
   #:export (factorize-uri
 
             flatten
@@ -377,40 +378,53 @@ separated by PRED."
                                       (chr (char-downcase chr)))
                                     name)))
 
+(define (topological-sort nodes
+                          node-dependencies
+                          node-name)
+  "Perform a breadth-first traversal of the graph rooted at NODES, a list of
+nodes, and return the list of nodes sorted in topological order.  Call
+NODE-DEPENDENCIES to obtain the dependencies of a node, and NODE-NAME to
+obtain a node's uniquely identifying \"key\"."
+  (let loop ((nodes nodes)
+             (result '())
+             (visited (set)))
+    (match nodes
+      (()
+       result)
+      ((head . tail)
+       (if (set-contains? visited (node-name head))
+           (loop tail result visited)
+           (let ((dependencies (node-dependencies head)))
+             (loop (append dependencies tail)
+                   (cons head result)
+                   (set-insert (node-name head) visited))))))))
+
 (define* (recursive-import package-name repo
                            #:key repo->guix-package guix-name
                            #:allow-other-keys)
-  "Generate a stream of package expressions for PACKAGE-NAME and all its
-dependencies."
-  (define (exists? dependency)
-    (not (null? (find-packages-by-name (guix-name dependency)))))
-  (define initial-state (list #f (list package-name) (list)))
-  (define (step state)
-    (match state
-      ((prev (next . rest) done)
-       (define (handle? dep)
-         (and
-           (not (equal? dep next))
-           (not (member dep done))
-           (not (exists? dep))))
-       (receive (package . dependencies) (repo->guix-package next repo)
-         (list
-           (if package package '()) ;; default #f on failure would interrupt
-           (if package
-             (lset-union equal? rest (filter handle? (car dependencies)))
-             rest)
-           (cons next done))))
-      ((prev '() done)
-       (list #f '() done))))
-
-  ;; Generate a lazy stream of package expressions for all unknown
-  ;; dependencies in the graph.
-  (stream-unfold
-    ;; map: produce a stream element
-    (match-lambda ((latest queue done) latest))
-    ;; predicate
-    (match-lambda ((latest queue done) latest))
-    ;; generator: update the queue
-    step
-    ;; initial state
-    (step initial-state)))
+  "Return a stream of package expressions for PACKAGE-NAME and all its
+dependencies, sorted in topological order.  For each package,
+call (REPO->GUIX-PACKAGE NAME REPO), which should return a package expression
+and a list of dependencies; call (GUIX-NAME NAME) to obtain the Guix package
+name corresponding to the upstream name."
+  (define-record-type <node>
+    (make-node name package dependencies)
+    node?
+    (name         node-name)
+    (package      node-package)
+    (dependencies node-dependencies))
+
+  (define (exists? name)
+    (not (null? (find-packages-by-name (guix-name name)))))
+
+  (define (lookup-node name)
+    (receive (package dependencies) (repo->guix-package name repo)
+      (make-node name package dependencies)))
+
+  (map node-package
+       (topological-sort (list (lookup-node package-name))
+                         (lambda (node)
+                           (map lookup-node
+                                (remove exists?
+                                        (node-dependencies node))))
+                         node-name)))
diff --git a/guix/profiles.scm b/guix/profiles.scm
index f5e5cc33d6..616605151e 100644
--- a/guix/profiles.scm
+++ b/guix/profiles.scm
@@ -1727,7 +1727,9 @@ because the NUMBER is zero.)"
 (define %profile-directory
   (string-append %state-directory "/profiles/"
                  (or (and=> (or (getenv "USER")
-                                (getenv "LOGNAME"))
+                                (getenv "LOGNAME")
+                                (false-if-exception
+                                 (passwd:name (getpwuid (getuid)))))
                             (cut string-append "per-user/" <>))
                      "default")))
 
diff --git a/guix/scripts/import/cran.scm b/guix/scripts/import/cran.scm
index b6592f78a9..d6f371ef3a 100644
--- a/guix/scripts/import/cran.scm
+++ b/guix/scripts/import/cran.scm
@@ -27,7 +27,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-cran))
@@ -98,10 +97,8 @@ Import and convert the CRAN package for PACKAGE-NAME.\n"))
        (if (assoc-ref opts 'recursive)
            ;; Recursive import
            (map package->definition
-                (reverse
-                 (stream->list
-                  (cran-recursive-import package-name
-                                         (or (assoc-ref opts 'repo) 'cran)))))
+                (cran-recursive-import package-name
+                                       (or (assoc-ref opts 'repo) 'cran)))
            ;; Single import
            (let ((sexp (cran->guix-package package-name
                                            (or (assoc-ref opts 'repo) 'cran))))
diff --git a/guix/scripts/import/crate.scm b/guix/scripts/import/crate.scm
index 4690cceb4d..92034dab3c 100644
--- a/guix/scripts/import/crate.scm
+++ b/guix/scripts/import/crate.scm
@@ -28,7 +28,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-crate))
@@ -101,9 +100,7 @@ Import and convert the crate.io package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (crate-recursive-import name))))
+                (crate-recursive-import name))
            (let ((sexp (crate->guix-package name version)))
              (unless sexp
                (leave (G_ "failed to download meta-data for package '~a'~%")
diff --git a/guix/scripts/import/elpa.scm b/guix/scripts/import/elpa.scm
index f1ed5016ba..d270d2b4bc 100644
--- a/guix/scripts/import/elpa.scm
+++ b/guix/scripts/import/elpa.scm
@@ -27,7 +27,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-elpa))
@@ -101,10 +100,8 @@ Import the latest package named PACKAGE-NAME from an ELPA repository.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (elpa-recursive-import package-name
-                                         (or (assoc-ref opts 'repo) 'gnu)))))
+                (elpa-recursive-import package-name
+                                       (or (assoc-ref opts 'repo) 'gnu)))
            (let ((sexp (elpa->guix-package package-name (assoc-ref opts 'repo))))
              (unless sexp
                (leave (G_ "failed to download package '~a'~%") package-name))
diff --git a/guix/scripts/import/gem.scm b/guix/scripts/import/gem.scm
index b6d9ccaae4..c64596b514 100644
--- a/guix/scripts/import/gem.scm
+++ b/guix/scripts/import/gem.scm
@@ -26,7 +26,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-gem))
@@ -95,9 +94,7 @@ Import and convert the RubyGems package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (gem-recursive-import package-name 'rubygems))))
+                (gem-recursive-import package-name 'rubygems))
            (let ((sexp (gem->guix-package package-name)))
              (unless sexp
                (leave (G_ "failed to download meta-data for package '~a'~%")
diff --git a/guix/scripts/import/hackage.scm b/guix/scripts/import/hackage.scm
index f4aac61078..710e786a79 100644
--- a/guix/scripts/import/hackage.scm
+++ b/guix/scripts/import/hackage.scm
@@ -27,7 +27,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-hackage))
@@ -130,9 +129,7 @@ version.\n"))
                              `(define-public ,(string->symbol name)
                                 ,pkg))
                             (_ #f))
-                          (reverse
-                           (stream->list
-                            (apply hackage-recursive-import arguments))))
+                          (apply hackage-recursive-import arguments))
                      ;; Single import
                      (apply hackage->guix-package arguments))))
       (unless sexp (error-fn))
diff --git a/guix/scripts/import/opam.scm b/guix/scripts/import/opam.scm
index 2d249a213f..20da1437fe 100644
--- a/guix/scripts/import/opam.scm
+++ b/guix/scripts/import/opam.scm
@@ -25,7 +25,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-opam))
@@ -94,9 +93,7 @@ Import and convert the opam package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (opam-recursive-import package-name))))
+                (opam-recursive-import package-name))
            ;; Single import
            (let ((sexp (opam->guix-package package-name)))
              (unless sexp
diff --git a/guix/scripts/import/pypi.scm b/guix/scripts/import/pypi.scm
index 7bd83818ba..33167174e2 100644
--- a/guix/scripts/import/pypi.scm
+++ b/guix/scripts/import/pypi.scm
@@ -26,7 +26,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-pypi))
@@ -95,9 +94,7 @@ Import and convert the PyPI package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (pypi-recursive-import package-name))))
+                (pypi-recursive-import package-name))
            ;; Single import
            (let ((sexp (pypi->guix-package package-name)))
              (unless sexp
diff --git a/guix/scripts/import/stackage.scm b/guix/scripts/import/stackage.scm
index b4b12581bf..d77328dcbf 100644
--- a/guix/scripts/import/stackage.scm
+++ b/guix/scripts/import/stackage.scm
@@ -27,7 +27,6 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
-  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-stackage))
@@ -110,9 +109,7 @@ Import and convert the LTS Stackage package for PACKAGE-NAME.\n"))
                              `(define-public ,(string->symbol name)
                                 ,pkg))
                             (_ #f))
-                          (reverse
-                           (stream->list
-                            (apply stackage-recursive-import arguments))))
+                          (apply stackage-recursive-import arguments))
                      ;; Single import
                      (apply stackage->guix-package arguments))))
       (unless sexp (error-fn))
diff --git a/guix/scripts/lint.scm b/guix/scripts/lint.scm
index 1668d02992..8d08c484f5 100644
--- a/guix/scripts/lint.scm
+++ b/guix/scripts/lint.scm
@@ -9,6 +9,7 @@
 ;;; Copyright © 2017 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2017, 2018 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2018, 2019 Arun Isaac <arunisaac@systemreboot.net>
+;;; Copyright © 2019 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -30,6 +31,7 @@
   #:use-module (guix lint)
   #:use-module (guix ui)
   #:use-module (guix scripts)
+  #:use-module (guix scripts build)
   #:use-module (gnu packages)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
@@ -94,6 +96,9 @@ run the checkers on all packages.\n"))
   -c, --checkers=CHECKER1,CHECKER2...
                          only run the specified checkers"))
   (display (G_ "
+  -L, --load-path=DIR    prepend DIR to the package module search path"))
+  (newline)
+  (display (G_ "
   -h, --help             display this help and exit"))
   (display (G_ "
   -l, --list-checkers    display the list of available lint checkers"))
@@ -128,6 +133,9 @@ run the checkers on all packages.\n"))
                               %local-checkers
                               (alist-delete 'checkers
                                             result))))
+        (find (lambda (option)
+                (member "load-path" (option-names option)))
+              %standard-build-options)
         (option '(#\h "help") #f #f
                 (lambda args
                   (show-help)
diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index 61d18e2609..bbacc93bc0 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -334,6 +334,16 @@ added to the pack."
   (define environment
     (singularity-environment-file profile))
 
+  (define symlinks*
+    ;; Singularity requires /bin (specifically /bin/sh), so ensure that
+    ;; symlink is created.
+    (if (find (match-lambda
+                (("/bin" . _) #t)
+                (_            #f))
+              symlinks)
+        symlinks
+        `(("/bin" -> "bin") ,@symlinks)))
+
   (define build
     (with-imported-modules (source-module-closure
                             '((guix build utils)
@@ -407,7 +417,7 @@ added to the pack."
                                         "s" "777" "0" "0"
                                         (relative-file-name (dirname source)
                                                             target)))))))
-                      '#$symlinks)
+                      '#$symlinks*)
 
                    "-p" "/.singularity.d d 555 0 0"
 
@@ -1049,9 +1059,18 @@ Create a bundle of PACKAGE.\n"))
                  (entry-point    (assoc-ref opts 'entry-point))
                  (profile-name   (assoc-ref opts 'profile-name))
                  (gc-root        (assoc-ref opts 'gc-root)))
+            (define (lookup-package package)
+              (manifest-lookup manifest (manifest-pattern (name package))))
+
             (when (null? (manifest-entries manifest))
               (warning (G_ "no packages specified; building an empty pack~%")))
 
+            (when (and (eq? pack-format 'squashfs)
+                       (not (any lookup-package '("bash" "bash-minimal"))))
+              (warning (G_ "Singularity requires you to provide a shell~%"))
+              (display-hint (G_ "Add @code{bash} or @code{bash-minimal} \
+to your package list.")))
+
             (run-with-store store
               (mlet* %store-monad ((profile (profile-derivation
                                              manifest
diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm
index 19410ad141..04cc51829d 100644
--- a/guix/scripts/pull.scm
+++ b/guix/scripts/pull.scm
@@ -60,6 +60,7 @@
   #:use-module (ice-9 format)
   #:export (display-profile-content
             channel-list
+            channel-commit-hyperlink
             with-git-error-handling
             guix-pull))
 
diff --git a/guix/scripts/system.scm b/guix/scripts/system.scm
index 5f0dce2093..3e9570753d 100644
--- a/guix/scripts/system.scm
+++ b/guix/scripts/system.scm
@@ -36,9 +36,11 @@
   #:use-module (guix records)
   #:use-module (guix profiles)
   #:use-module (guix scripts)
+  #:use-module (guix channels)
   #:use-module (guix scripts build)
   #:autoload   (guix scripts package) (delete-generations
                                        delete-matching-generations)
+  #:autoload   (guix scripts pull) (channel-commit-hyperlink)
   #:use-module (guix graph)
   #:use-module (guix scripts graph)
   #:use-module (guix scripts system reconfigure)
@@ -456,9 +458,30 @@ list of services."
 ;;; Generations.
 ;;;
 
+(define (sexp->channel sexp)
+  "Return the channel corresponding to SEXP, an sexp as found in the
+\"provenance\" file produced by 'provenance-service-type'."
+  (match sexp
+    (('channel ('name name)
+               ('url url)
+               ('branch branch)
+               ('commit commit))
+     (channel (name name) (url url)
+              (branch branch) (commit commit)))))
+
 (define* (display-system-generation number
                                     #:optional (profile %system-profile))
   "Display a summary of system generation NUMBER in a human-readable format."
+  (define (display-channel channel)
+    (format #t     "    ~a:~%" (channel-name channel))
+    (format #t (G_ "      repository URL: ~a~%") (channel-url channel))
+    (when (channel-branch channel)
+      (format #t (G_ "      branch: ~a~%") (channel-branch channel)))
+    (format #t (G_ "      commit: ~a~%")
+            (if (supports-hyperlinks?)
+                (channel-commit-hyperlink channel)
+                (channel-commit channel))))
+
   (unless (zero? number)
     (let* ((generation  (generation-file-name profile number))
            (params      (read-boot-parameters-file generation))
@@ -468,7 +491,13 @@ list of services."
            (root-device (if (bytevector? root)
                             (uuid->string root)
                             root))
-           (kernel      (boot-parameters-kernel params)))
+           (kernel      (boot-parameters-kernel params))
+           (provenance  (catch 'system-error
+                          (lambda ()
+                            (call-with-input-file
+                                (string-append generation "/provenance")
+                              read))
+                          (const #f))))
       (display-generation profile number)
       (format #t (G_ "  file name: ~a~%") generation)
       (format #t (G_ "  canonical file name: ~a~%") (readlink* generation))
@@ -495,7 +524,23 @@ list of services."
                     (else
                      root-device)))
 
-      (format #t (G_ "  kernel: ~a~%") kernel))))
+      (format #t (G_ "  kernel: ~a~%") kernel)
+
+      (match provenance
+        (#f #t)
+        (('provenance ('version 0)
+                      ('channels channels ...)
+                      ('configuration-file config-file))
+         (unless (null? channels)
+           ;; TRANSLATORS: Here "channel" is the same terminology as used in
+           ;; "guix describe" and "guix pull --channels".
+           (format #t (G_ "  channels:~%"))
+           (for-each display-channel (map sexp->channel channels)))
+         (when config-file
+           (format #t (G_ "  configuration file: ~a~%")
+                   (if (supports-hyperlinks?)
+                       (file-hyperlink config-file)
+                       config-file))))))))
 
 (define* (list-generations pattern #:optional (profile %system-profile))
   "Display in a human-readable format all the system generations matching
@@ -722,7 +767,9 @@ and TARGET arguments."
      (return (primitive-eval (lowered-gexp-sexp lowered))))))
 
 (define* (perform-action action os
-                         #:key skip-safety-checks?
+                         #:key
+                         save-provenance?
+                         skip-safety-checks?
                          install-bootloader?
                          dry-run? derivations-only?
                          use-substitutes? bootloader-target target
@@ -875,6 +922,8 @@ Some ACTIONS support additional ARGS.\n"))
   (display (G_ "\
    roll-back        switch to the previous operating system configuration\n"))
   (display (G_ "\
+   describe         describe the current system\n"))
+  (display (G_ "\
    list-generations list the system generations\n"))
   (display (G_ "\
    switch-generation switch to an existing operating system configuration\n"))
@@ -918,16 +967,18 @@ Some ACTIONS support additional ARGS.\n"))
   (display (G_ "
       --no-bootloader    for 'init', do not install a bootloader"))
   (display (G_ "
+      --save-provenance  save provenance information"))
+  (display (G_ "
       --share=SPEC       for 'vm', share host file system according to SPEC"))
   (display (G_ "
+      --expose=SPEC      for 'vm', expose host file system according to SPEC"))
+  (display (G_ "
   -N, --network          for 'container', allow containers to access the network"))
   (display (G_ "
   -r, --root=FILE        for 'vm', 'vm-image', 'disk-image', 'container',
                          and 'build', make FILE a symlink to the result, and
                          register it as a garbage collector root"))
   (display (G_ "
-      --expose=SPEC      for 'vm', expose host file system according to SPEC"))
-  (display (G_ "
       --full-boot        for 'vm', make a full boot sequence"))
   (display (G_ "
       --skip-checks      skip file system and initrd module safety checks"))
@@ -979,6 +1030,9 @@ Some ACTIONS support additional ARGS.\n"))
          (option '("full-boot") #f #f
                  (lambda (opt name arg result)
                    (alist-cons 'full-boot? #t result)))
+         (option '("save-provenance") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'save-provenance? #t result)))
          (option '("skip-checks") #f #f
                  (lambda (opt name arg result)
                    (alist-cons 'skip-safety-checks? #t result)))
@@ -1047,25 +1101,33 @@ resulting from command-line parsing."
              file-or-exp))
     obj)
 
+  (define save-provenance?
+    (or (assoc-ref opts 'save-provenance?)
+        (memq action '(init reconfigure))))
+
   (let* ((file        (match args
                         (() #f)
                         ((x . _) x)))
          (expr        (assoc-ref opts 'expression))
          (system      (assoc-ref opts 'system))
          (target      (assoc-ref opts 'target))
-         (os          (ensure-operating-system
-                       (or file expr)
-                       (cond
-                        ((and expr file)
-                         (leave
-                          (G_ "both file and expression cannot be specified~%")))
-                        (expr
-                         (read/eval expr))
-                        (file
-                         (load* file %user-module
-                                #:on-error (assoc-ref opts 'on-error)))
-                        (else
-                         (leave (G_ "no configuration specified~%"))))))
+         (transform   (if save-provenance?
+                          (cut operating-system-with-provenance <> file)
+                          identity))
+         (os          (transform
+                       (ensure-operating-system
+                        (or file expr)
+                        (cond
+                         ((and expr file)
+                          (leave
+                           (G_ "both file and expression cannot be specified~%")))
+                         (expr
+                          (read/eval expr))
+                         (file
+                          (load* file %user-module
+                                 #:on-error (assoc-ref opts 'on-error)))
+                         (else
+                          (leave (G_ "no configuration specified~%")))))))
 
          (dry?        (assoc-ref opts 'dry-run?))
          (bootloader? (assoc-ref opts 'install-bootloader?))
@@ -1136,6 +1198,12 @@ argument list and OPTS is the option alist."
                       ((pattern) pattern)
                       (x (leave (G_ "wrong number of arguments~%"))))))
        (list-generations pattern)))
+    ((describe)
+     (match (generation-number %system-profile)
+       (0
+        (error (G_ "no system generation, nothing to describe~%")))
+       (generation
+        (display-system-generation generation))))
     ((search)
      (apply (resolve-subcommand "search") args))
     ;; The following commands need to use the store, but they do not need an
@@ -1175,7 +1243,8 @@ argument list and OPTS is the option alist."
           (case action
             ((build container vm vm-image disk-image reconfigure init
               extension-graph shepherd-graph
-              list-generations delete-generations roll-back
+              list-generations describe
+              delete-generations roll-back
               switch-generation search docker-image)
              (alist-cons 'action action result))
             (else (leave (G_ "~a: unknown action~%") action))))))