lint: Move the linting code to a different module.

To try and move towards making programatic access to the linting code easier,
this commit separates out the linting script, from the linting functionality
that it uses.

* guix/scripts/lint.scm (emit-warnings): Alter to to not use match-lambda, as
<lint-warning> isn't accessible.
(<lint-warning>, lint-warning, make-lint-warning, lint-warning?,
lint-warning-message, lint-warning-message-text, lint-warning-message-data,
lint-warning-location, package-file, %make-warning make-warning,
<lint-checker>, lint-checker, make-lint-checker, lint-checker?,
lint-checker-name, lint-checker-description, lint-checker-check,
properly-starts-sentance?, starts-with-abbreviation?, %quoted-identifier-rx,
check-description-style, package-input-intersection,
check-inputs-should-be-native, check-inputs-should-not-be-an-input-at-all,
package-name-regexp, check-synopsis-style, probe-uri,
tls-certificate-error-string, validate-uri, check-home-page,
%distro-directory, check-patch-file-names, escape-quotes,
official-gnu-packages*, check-gnu-synopsis+description, origin-uris,
check-source, check-source-file-name, check-source-unstable-tarball,
check-mirror-url, check-github-url, check-derivation, check-license,
call-with-networking-fail-safe, with-networking-fail-safe,
current-vulnerabilities*, package-vulnerabilities, check-vulnerabilities,
check-for-updates, report-tabulations, report-trailing-white-space,
report-long-line, %hanging-paren-rx, report-lone-parantheses,
%formatting-reporters, report-formatting-issues, check-formatting, %checkers):
Move to…
* guix/lint.scm: … here
* po/guix/POTFILES.in: Add guix/lint.scm.
* Makefile.am: Add guix/lint.scm.
* tests/lint.scm: Change to import (guix lint), rather than (guix scripts lint).

1 files changed, 19 insertions, 1201 deletions

diff --git a/guix/scripts/lint.scm b/guix/scripts/lint.scm
index 4eb7e0e200..1c46fba16b 100644
--- a/guix/scripts/lint.scm
+++ b/guix/scripts/lint.scm
@@ -26,1224 +26,32 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (guix scripts lint)
-  #:use-module ((guix store) #:hide (close-connection))
-  #:use-module (guix base32)
-  #:use-module (guix download)
-  #:use-module (guix ftp-client)
-  #:use-module (guix http-client)
   #:use-module (guix packages)
-  #:use-module (guix licenses)
-  #:use-module (guix records)
-  #:use-module (guix grafts)
+  #:use-module (guix lint)
   #:use-module (guix ui)
-  #:use-module (guix upstream)
-  #:use-module (guix utils)
-  #:use-module (guix memoization)
   #:use-module (guix scripts)
-  #:use-module (guix gnu-maintenance)
-  #:use-module (guix monads)
-  #:use-module (guix cve)
   #:use-module (gnu packages)
   #:use-module (ice-9 match)
-  #:use-module (ice-9 regex)
   #:use-module (ice-9 format)
-  #:use-module (web client)
-  #:use-module (web uri)
-  #:use-module ((guix build download)
-                #:select (maybe-expand-mirrors
-                          (open-connection-for-uri
-                           . guix:open-connection-for-uri)
-                          close-connection))
-  #:use-module (web request)
-  #:use-module (web response)
   #:use-module (srfi srfi-1)
-  #:use-module (srfi srfi-6)                      ;Unicode string ports
-  #:use-module (srfi srfi-9)
-  #:use-module (srfi srfi-11)
-  #:use-module (srfi srfi-26)
-  #:use-module (srfi srfi-34)
-  #:use-module (srfi srfi-35)
   #:use-module (srfi srfi-37)
-  #:use-module (ice-9 rdelim)
   #:export (guix-lint
-            check-description-style
-            check-inputs-should-be-native
-            check-inputs-should-not-be-an-input-at-all
-            check-patch-file-names
-            check-synopsis-style
-            check-derivation
-            check-home-page
-            check-source
-            check-source-file-name
-            check-source-unstable-tarball
-            check-mirror-url
-            check-github-url
-            check-license
-            check-vulnerabilities
-            check-for-updates
-            check-formatting
-            run-checkers
-
-            lint-warning
-            lint-warning?
-            lint-warning-package
-            lint-warning-message
-            lint-warning-message-text
-            lint-warning-message-data
-            lint-warning-location
-
-            %checkers
-            lint-checker
-            lint-checker?
-            lint-checker-name
-            lint-checker-description
-            lint-checker-check))
-
-
-;;;
-;;; Warnings
-;;;
-
-(define-record-type* <lint-warning>
-  lint-warning make-lint-warning
-  lint-warning?
-  (package       lint-warning-package)
-  (message-text  lint-warning-message-text)
-  (message-data  lint-warning-message-data
-                 (default '()))
-  (location      lint-warning-location
-                 (default #f)))
-
-(define (lint-warning-message warning)
-  (apply format #f
-         (G_ (lint-warning-message-text warning))
-         (lint-warning-message-data warning)))
-
-(define (package-file package)
-  (location-file
-   (package-location package)))
-
-(define* (%make-warning package message-text
-                        #:optional (message-data '())
-                        #:key field location)
-  (make-lint-warning
-   package
-   message-text
-   message-data
-   (or location
-       (package-field-location package field)
-       (package-location package))))
-
-(define-syntax make-warning
-  (syntax-rules (G_)
-    ((_ package (G_ message) rest ...)
-     (%make-warning package message rest ...))))
+            run-checkers))
 
 (define (emit-warnings warnings)
   ;; Emit a warning about PACKAGE, printing the location of FIELD if it is
   ;; given, the location of PACKAGE otherwise, the full name of PACKAGE and the
   ;; provided MESSAGE.
   (for-each
-   (match-lambda
-     (($ <lint-warning> package message-text message-data loc)
-      (format (guix-warning-port) "~a: ~a@~a: ~a~%"
-              (location->string loc)
-              (package-name package) (package-version package)
-              (apply format #f (G_ message-text) message-data))))
+   (lambda (lint-warning)
+     (let ((package (lint-warning-package lint-warning))
+           (loc     (lint-warning-location lint-warning)))
+       (format (guix-warning-port) "~a: ~a@~a: ~a~%"
+               (location->string loc)
+               (package-name package) (package-version package)
+               (lint-warning-message lint-warning))))
    warnings))
 
-
-;;;
-;;; Checkers
-;;;
-
-(define-record-type* <lint-checker>
-  lint-checker make-lint-checker
-  lint-checker?
-  ;; TODO: add a 'certainty' field that shows how confident we are in the
-  ;; checker. Then allow users to only run checkers that have a certain
-  ;; 'certainty' level.
-  (name        lint-checker-name)
-  (description lint-checker-description)
-  (check       lint-checker-check))
-
-(define (list-checkers-and-exit)
-  ;; Print information about all available checkers and exit.
-  (format #t (G_ "Available checkers:~%"))
-  (for-each (lambda (checker)
-              (format #t "- ~a: ~a~%"
-                      (lint-checker-name checker)
-                      (G_ (lint-checker-description checker))))
-            %checkers)
-  (exit 0))
-
-(define (properly-starts-sentence? s)
-  (string-match "^[(\"'`[:upper:][:digit:]]" s))
-
-(define (starts-with-abbreviation? s)
-  "Return #t if S starts with what looks like an abbreviation or acronym."
-  (string-match "^[A-Z][A-Z0-9]+\\>" s))
-
-(define %quoted-identifier-rx
-  ;; A quoted identifier, like 'this'.
-  (make-regexp "['`][[:graph:]]+'"))
-
-(define (check-description-style package)
-  ;; Emit a warning if stylistic issues are found in the description of PACKAGE.
-  (define (check-not-empty description)
-    (if (string-null? description)
-        (list
-         (make-warning package
-                       (G_ "description should not be empty")
-                       #:field 'description))
-        '()))
-
-  (define (check-texinfo-markup description)
-    "Check that DESCRIPTION can be parsed as a Texinfo fragment.  If the
-markup is valid return a plain-text version of DESCRIPTION, otherwise #f."
-    (catch #t
-      (lambda () (texi->plain-text description))
-      (lambda (keys . args)
-        (make-warning package
-                      (G_ "Texinfo markup in description is invalid")
-                      #:field 'description))))
-
-  (define (check-trademarks description)
-    "Check that DESCRIPTION does not contain '™' or '®' characters.  See
-http://www.gnu.org/prep/standards/html_node/Trademarks.html."
-    (match (string-index description (char-set #\™ #\®))
-      ((and (? number?) index)
-       (list
-        (make-warning package
-                      (G_ "description should not contain ~
-trademark sign '~a' at ~d")
-                      (list (string-ref description index) index)
-                      #:field 'description)))
-      (else '())))
-
-  (define (check-quotes description)
-    "Check whether DESCRIPTION contains single quotes and suggest @code."
-    (if (regexp-exec %quoted-identifier-rx description)
-        (list
-         (make-warning package
-                       ;; TRANSLATORS: '@code' is Texinfo markup and must be kept
-                       ;; as is.
-                       (G_ "use @code or similar ornament instead of quotes")
-                       #:field 'description))
-        '()))
-
-  (define (check-proper-start description)
-    (if (or (string-null? description)
-            (properly-starts-sentence? description)
-            (string-prefix-ci? (package-name package) description))
-        '()
-        (list
-         (make-warning
-          package
-          (G_ "description should start with an upper-case letter or digit")
-          #:field 'description))))
-
-  (define (check-end-of-sentence-space description)
-    "Check that an end-of-sentence period is followed by two spaces."
-    (let ((infractions
-           (reverse (fold-matches
-                     "\\. [A-Z]" description '()
-                     (lambda (m r)
-                       ;; Filter out matches of common abbreviations.
-                       (if (find (lambda (s)
-                                   (string-suffix-ci? s (match:prefix m)))
-                                 '("i.e" "e.g" "a.k.a" "resp"))
-                           r (cons (match:start m) r)))))))
-      (if (null? infractions)
-          '()
-          (list
-           (make-warning package
-                         (G_ "sentences in description should be followed ~
-by two spaces; possible infraction~p at ~{~a~^, ~}")
-                         (list (length infractions)
-                               infractions)
-                         #:field 'description)))))
-
-  (let ((description (package-description package)))
-    (if (string? description)
-        (append
-         (check-not-empty description)
-         (check-quotes description)
-         (check-trademarks description)
-         ;; Use raw description for this because Texinfo rendering
-         ;; automatically fixes end of sentence space.
-         (check-end-of-sentence-space description)
-         (match (check-texinfo-markup description)
-           ((and warning (? lint-warning?)) (list warning))
-           (plain-description
-            (check-proper-start plain-description))))
-        (list
-         (make-warning package
-                       (G_ "invalid description: ~s")
-                       (list description)
-                       #:field 'description)))))
-
-(define (package-input-intersection inputs-to-check input-names)
-  "Return the intersection between INPUTS-TO-CHECK, the list of input tuples
-of a package, and INPUT-NAMES, a list of package specifications such as
-\"glib:bin\"."
-  (match inputs-to-check
-    (((labels packages . outputs) ...)
-     (filter-map (lambda (package output)
-                   (and (package? package)
-                        (let ((input (string-append
-                                      (package-name package)
-                                      (if (> (length output) 0)
-                                          (string-append ":" (car output))
-                                          ""))))
-                          (and (member input input-names)
-                               input))))
-                 packages outputs))))
-
-(define (check-inputs-should-be-native package)
-  ;; Emit a warning if some inputs of PACKAGE are likely to belong to its
-  ;; native inputs.
-  (let ((inputs (package-inputs package))
-        (input-names
-         '("pkg-config"
-            "cmake"
-            "extra-cmake-modules"
-            "glib:bin"
-            "intltool"
-            "itstool"
-            "qttools"
-            "python-coverage" "python2-coverage"
-            "python-cython" "python2-cython"
-            "python-docutils" "python2-docutils"
-            "python-mock" "python2-mock"
-            "python-nose" "python2-nose"
-            "python-pbr" "python2-pbr"
-            "python-pytest" "python2-pytest"
-            "python-pytest-cov" "python2-pytest-cov"
-            "python-setuptools-scm" "python2-setuptools-scm"
-            "python-sphinx" "python2-sphinx")))
-    (map (lambda (input)
-           (make-warning
-            package
-            (G_ "'~a' should probably be a native input")
-            (list input)
-            #:field 'inputs))
-         (package-input-intersection inputs input-names))))
-
-(define (check-inputs-should-not-be-an-input-at-all package)
-  ;; Emit a warning if some inputs of PACKAGE are likely to should not be
-  ;; an input at all.
-  (let ((input-names '("python-setuptools"
-                       "python2-setuptools"
-                       "python-pip"
-                       "python2-pip")))
-    (map (lambda (input)
-           (make-warning
-            package
-            (G_ "'~a' should probably not be an input at all")
-            (list input)
-            #:field 'inputs))
-         (package-input-intersection (package-direct-inputs package)
-                                     input-names))))
-
-(define (package-name-regexp package)
-  "Return a regexp that matches PACKAGE's name as a word at the beginning of a
-line."
-  (make-regexp (string-append "^" (regexp-quote (package-name package))
-                              "\\>")
-               regexp/icase))
-
-(define (check-synopsis-style package)
-  ;; Emit a warning if stylistic issues are found in the synopsis of PACKAGE.
-  (define (check-final-period synopsis)
-    ;; Synopsis should not end with a period, except for some special cases.
-    (if (and (string-suffix? "." synopsis)
-             (not (string-suffix? "etc." synopsis)))
-        (list
-         (make-warning package
-                       (G_ "no period allowed at the end of the synopsis")
-                       #:field 'synopsis))
-        '()))
-
-  (define check-start-article
-    ;; Skip this check for GNU packages, as suggested by Karl Berry's reply to
-    ;; <http://lists.gnu.org/archive/html/bug-womb/2014-11/msg00000.html>.
-    (if (false-if-exception (gnu-package? package))
-        (const '())
-        (lambda (synopsis)
-          (if (or (string-prefix-ci? "A " synopsis)
-                  (string-prefix-ci? "An " synopsis))
-              (list
-               (make-warning package
-                             (G_ "no article allowed at the beginning of \
-the synopsis")
-                             #:field 'synopsis))
-              '()))))
-
-  (define (check-synopsis-length synopsis)
-    (if (>= (string-length synopsis) 80)
-        (list
-         (make-warning package
-                       (G_ "synopsis should be less than 80 characters long")
-                       #:field 'synopsis))
-        '()))
-
-  (define (check-proper-start synopsis)
-    (if (properly-starts-sentence? synopsis)
-        '()
-        (list
-         (make-warning package
-                       (G_ "synopsis should start with an upper-case letter or digit")
-                       #:field 'synopsis))))
-
-  (define (check-start-with-package-name synopsis)
-    (if (and (regexp-exec (package-name-regexp package) synopsis)
-               (not (starts-with-abbreviation? synopsis)))
-        (list
-         (make-warning package
-                       (G_ "synopsis should not start with the package name")
-                       #:field 'synopsis))
-        '()))
-
-  (define (check-texinfo-markup synopsis)
-    "Check that SYNOPSIS can be parsed as a Texinfo fragment.  If the
-markup is valid return a plain-text version of SYNOPSIS, otherwise #f."
-    (catch #t
-      (lambda ()
-        (texi->plain-text synopsis)
-        '())
-      (lambda (keys . args)
-        (list
-         (make-warning package
-                       (G_ "Texinfo markup in synopsis is invalid")
-                       #:field 'synopsis)))))
-
-  (define checks
-    (list check-proper-start
-          check-final-period
-          check-start-article
-          check-start-with-package-name
-          check-synopsis-length
-          check-texinfo-markup))
-
-  (match (package-synopsis package)
-    (""
-     (list
-      (make-warning package
-                    (G_ "synopsis should not be empty")
-                    #:field 'synopsis)))
-    ((? string? synopsis)
-     (append-map
-      (lambda (proc)
-        (proc synopsis))
-      checks))
-    (invalid
-     (list
-      (make-warning package
-                    (G_ "invalid synopsis: ~s")
-                    (list invalid)
-                    #:field 'synopsis)))))
-
-(define* (probe-uri uri #:key timeout)
-  "Probe URI, a URI object, and return two values: a symbol denoting the
-probing status, such as 'http-response' when we managed to get an HTTP
-response from URI, and additional details, such as the actual HTTP response.
-
-TIMEOUT is the maximum number of seconds (possibly an inexact number) to wait
-for connections to complete; when TIMEOUT is #f, wait as long as needed."
-  (define headers
-    '((User-Agent . "GNU Guile")
-      (Accept . "*/*")))
-
-  (let loop ((uri     uri)
-             (visited '()))
-    (match (uri-scheme uri)
-      ((or 'http 'https)
-       (catch #t
-         (lambda ()
-           (let ((port    (guix:open-connection-for-uri
-                           uri #:timeout timeout))
-                 (request (build-request uri #:headers headers)))
-             (define response
-               (dynamic-wind
-                 (const #f)
-                 (lambda ()
-                   (write-request request port)
-                   (force-output port)
-                   (read-response port))
-                 (lambda ()
-                   (close-connection port))))
-
-             (case (response-code response)
-               ((302                    ; found (redirection)
-                 303                    ; see other
-                 307                    ; temporary redirection
-                 308)                   ; permanent redirection
-                (let ((location (response-location response)))
-                  (if (or (not location) (member location visited))
-                      (values 'http-response response)
-                      (loop location (cons location visited))))) ;follow the redirect
-               ((301)                   ; moved permanently
-                (let ((location (response-location response)))
-                  ;; Return RESPONSE, unless the final response as we follow
-                  ;; redirects is not 200.
-                  (if location
-                      (let-values (((status response2)
-                                    (loop location (cons location visited))))
-                        (case status
-                          ((http-response)
-                           (values 'http-response
-                                   (if (= 200 (response-code response2))
-                                       response
-                                       response2)))
-                          (else
-                           (values status response2))))
-                      (values 'http-response response)))) ;invalid redirect
-               (else
-                (values 'http-response response)))))
-         (lambda (key . args)
-           (case key
-             ((bad-header bad-header-component)
-              ;; This can happen if the server returns an invalid HTTP header,
-              ;; as is the case with the 'Date' header at sqlite.org.
-              (values 'invalid-http-response #f))
-             ((getaddrinfo-error system-error
-               gnutls-error tls-certificate-error)
-              (values key args))
-             (else
-              (apply throw key args))))))
-      ('ftp
-       (catch #t
-         (lambda ()
-           (let ((conn (ftp-open (uri-host uri) #:timeout timeout)))
-             (define response
-               (dynamic-wind
-                 (const #f)
-                 (lambda ()
-                   (ftp-chdir conn (dirname (uri-path uri)))
-                   (ftp-size conn (basename (uri-path uri))))
-                 (lambda ()
-                   (ftp-close conn))))
-             (values 'ftp-response '(ok))))
-         (lambda (key . args)
-           (case key
-             ((ftp-error)
-              (values 'ftp-response `(error ,@args)))
-             ((getaddrinfo-error system-error gnutls-error)
-              (values key args))
-             (else
-              (apply throw key args))))))
-      (_
-       (values 'unknown-protocol #f)))))
-
-(define (tls-certificate-error-string args)
-  "Return a string explaining the 'tls-certificate-error' arguments ARGS."
-  (call-with-output-string
-    (lambda (port)
-      (print-exception port #f
-                       'tls-certificate-error args))))
-
-(define (validate-uri uri package field)
-  "Return #t if the given URI can be reached, otherwise return a warning for
-PACKAGE mentionning the FIELD."
-  (let-values (((status argument)
-                (probe-uri uri #:timeout 3)))     ;wait at most 3 seconds
-    (case status
-      ((http-response)
-       (cond ((= 200 (response-code argument))
-              (match (response-content-length argument)
-                ((? number? length)
-                 ;; As of July 2016, SourceForge returns 200 (instead of 404)
-                 ;; with a small HTML page upon failure.  Attempt to detect
-                 ;; such malicious behavior.
-                 (or (> length 1000)
-                     (make-warning package
-                                   (G_ "URI ~a returned \
-suspiciously small file (~a bytes)")
-                                   (list (uri->string uri)
-                                         length)
-                                   #:field field)))
-                (_ #t)))
-             ((= 301 (response-code argument))
-              (if (response-location argument)
-                  (make-warning package
-                                (G_ "permanent redirect from ~a to ~a")
-                                (list (uri->string uri)
-                                      (uri->string
-                                       (response-location argument)))
-                                #:field field)
-                  (make-warning package
-                                (G_ "invalid permanent redirect \
-from ~a")
-                                (list (uri->string uri))
-                                #:field field)))
-             (else
-              (make-warning package
-                            (G_ "URI ~a not reachable: ~a (~s)")
-                            (list (uri->string uri)
-                                  (response-code argument)
-                                  (response-reason-phrase argument))
-                            #:field field))))
-      ((ftp-response)
-       (match argument
-         (('ok) #t)
-         (('error port command code message)
-          (make-warning package
-                        (G_ "URI ~a not reachable: ~a (~s)")
-                        (list (uri->string uri)
-                              code (string-trim-both message))
-                        #:field field))))
-      ((getaddrinfo-error)
-       (make-warning package
-                     (G_ "URI ~a domain not found: ~a")
-                     (list (uri->string uri)
-                           (gai-strerror (car argument)))
-                     #:field field))
-      ((system-error)
-       (make-warning package
-                     (G_ "URI ~a unreachable: ~a")
-                     (list (uri->string uri)
-                           (strerror
-                            (system-error-errno
-                             (cons status argument))))
-                     #:field field))
-      ((tls-certificate-error)
-       (make-warning package
-                     (G_ "TLS certificate error: ~a")
-                     (list (tls-certificate-error-string argument))
-                     #:field field))
-      ((invalid-http-response gnutls-error)
-       ;; Probably a misbehaving server; ignore.
-       #f)
-      ((unknown-protocol)                         ;nothing we can do
-       #f)
-      (else
-       (error "internal linter error" status)))))
-
-(define (check-home-page package)
-  "Emit a warning if PACKAGE has an invalid 'home-page' field, or if that
-'home-page' is not reachable."
-  (let ((uri (and=> (package-home-page package) string->uri)))
-    (cond
-     ((uri? uri)
-      (match (validate-uri uri package 'home-page)
-        ((and (? lint-warning? warning) warning)
-         (list warning))
-        (_ '())))
-     ((not (package-home-page package))
-      (if (or (string-contains (package-name package) "bootstrap")
-              (string=? (package-name package) "ld-wrapper"))
-          '()
-          (list
-           (make-warning package
-                         (G_ "invalid value for home page")
-                         #:field 'home-page))))
-     (else
-      (list
-       (make-warning package
-                     (G_ "invalid home page URL: ~s")
-                     (list (package-home-page package))
-                     #:field 'home-page))))))
-
-(define %distro-directory
-  (mlambda ()
-    (dirname (search-path %load-path "gnu.scm"))))
-
-(define (check-patch-file-names package)
-  "Emit a warning if the patches requires by PACKAGE are badly named or if the
-patch could not be found."
-  (guard (c ((message-condition? c)     ;raised by 'search-patch'
-             (list
-              ;; Use %make-warning, as condition-mesasge is already
-              ;; translated.
-              (%make-warning package (condition-message c)
-                             #:field 'patch-file-names))))
-    (define patches
-      (or (and=> (package-source package) origin-patches)
-          '()))
-
-    (append
-     (if (every (match-lambda        ;patch starts with package name?
-                  ((? string? patch)
-                   (and=> (string-contains (basename patch)
-                                           (package-name package))
-                          zero?))
-                  (_  #f))     ;must be an <origin> or something like that.
-                patches)
-         '()
-         (list
-          (make-warning
-           package
-           (G_ "file names of patches should start with the package name")
-           #:field 'patch-file-names)))
-
-     ;; Check whether we're reaching tar's maximum file name length.
-     (let ((prefix (string-length (%distro-directory)))
-           (margin (string-length "guix-0.13.0-10-123456789/"))
-           (max    99))
-       (filter-map (match-lambda
-                     ((? string? patch)
-                      (if (> (+ margin (if (string-prefix? (%distro-directory)
-                                                           patch)
-                                           (- (string-length patch) prefix)
-                                           (string-length patch)))
-                             max)
-                          (make-warning
-                           package
-                           (G_ "~a: file name is too long")
-                           (list (basename patch))
-                           #:field 'patch-file-names)
-                          #f))
-                     (_ #f))
-                   patches)))))
-
-(define (escape-quotes str)
-  "Replace any quote character in STR by an escaped quote character."
-  (list->string
-   (string-fold-right (lambda (chr result)
-                        (match chr
-                          (#\" (cons* #\\ #\"result))
-                          (_   (cons chr result))))
-                      '()
-                      str)))
-
-(define official-gnu-packages*
-  (mlambda ()
-    "A memoizing version of 'official-gnu-packages' that returns the empty
-list when something goes wrong, such as a networking issue."
-    (let ((gnus (false-if-exception (official-gnu-packages))))
-      (or gnus '()))))
-
-(define (check-gnu-synopsis+description package)
-  "Make sure that, if PACKAGE is a GNU package, it uses the synopsis and
-descriptions maintained upstream."
-  (match (find (lambda (descriptor)
-                 (string=? (gnu-package-name descriptor)
-                           (package-name package)))
-               (official-gnu-packages*))
-    (#f                                   ;not a GNU package, so nothing to do
-     '())
-    (descriptor                                   ;a genuine GNU package
-     (append
-      (let ((upstream   (gnu-package-doc-summary descriptor))
-            (downstream (package-synopsis package)))
-        (if (and upstream
-                 (or (not (string? downstream))
-                     (not (string=? upstream downstream))))
-            (list
-             (make-warning package
-                           (G_ "proposed synopsis: ~s~%")
-                           (list upstream)
-                           #:field 'synopsis))
-            '()))
-
-      (let ((upstream   (gnu-package-doc-description descriptor))
-            (downstream (package-description package)))
-        (if (and upstream
-                 (or (not (string? downstream))
-                     (not (string=? (fill-paragraph upstream 100)
-                                    (fill-paragraph downstream 100)))))
-            (list
-             (make-warning
-              package
-              (G_ "proposed description:~%     \"~a\"~%")
-              (list (fill-paragraph (escape-quotes upstream) 77 7))
-              #:field 'description))
-            '()))))))
-
-(define (origin-uris origin)
-  "Return the list of URIs (strings) for ORIGIN."
-  (match (origin-uri origin)
-    ((? string? uri)
-     (list uri))
-    ((uris ...)
-     uris)))
-
-(define (check-source package)
-  "Emit a warning if PACKAGE has an invalid 'source' field, or if that
-'source' is not reachable."
-  (define (warnings-for-uris uris)
-    (filter lint-warning?
-            (map
-             (lambda (uri)
-               (validate-uri uri package 'source))
-             (append-map (cut maybe-expand-mirrors <> %mirrors)
-                         uris))))
-
-  (let ((origin (package-source package)))
-    (if (and origin
-             (eqv? (origin-method origin) url-fetch))
-        (let* ((uris (map string->uri (origin-uris origin)))
-               (warnings (warnings-for-uris uris)))
-
-          ;; Just make sure that at least one of the URIs is valid.
-          (if (eq? (length uris) (length warnings))
-              ;; When everything fails, report all of WARNINGS, otherwise don't
-              ;; report anything.
-              ;;
-              ;; XXX: Ideally we'd still allow warnings to be raised if *some*
-              ;; URIs are unreachable, but distinguish that from the error case
-              ;; where *all* the URIs are unreachable.
-              (cons*
-               (make-warning package
-                             (G_ "all the source URIs are unreachable:")
-                             #:field 'source)
-               warnings)
-              '()))
-        '())))
-
-(define (check-source-file-name package)
-  "Emit a warning if PACKAGE's origin has no meaningful file name."
-  (define (origin-file-name-valid? origin)
-    ;; Return #f if the source file name contains only a version or is #f;
-    ;; indicates that the origin needs a 'file-name' field.
-    (let ((file-name (origin-actual-file-name origin))
-          (version (package-version package)))
-      (and file-name
-           ;; Common in many projects is for the filename to start
-           ;; with a "v" followed by the version,
-           ;; e.g. "v3.2.0.tar.gz".
-           (not (string-match (string-append "^v?" version) file-name)))))
-
-  (let ((origin (package-source package)))
-    (if (or (not origin) (origin-file-name-valid? origin))
-        '()
-        (list
-         (make-warning package
-                       (G_ "the source file name should contain the package name")
-                       #:field 'source)))))
-
-(define (check-source-unstable-tarball package)
-  "Emit a warning if PACKAGE's source is an autogenerated tarball."
-  (define (check-source-uri uri)
-    (if (and (string=? (uri-host (string->uri uri)) "github.com")
-             (match (split-and-decode-uri-path
-                     (uri-path (string->uri uri)))
-               ((_ _ "archive" _ ...) #t)
-               (_ #f)))
-        (make-warning package
-                      (G_ "the source URI should not be an autogenerated tarball")
-                      #:field 'source)
-        #f))
-
-  (let ((origin (package-source package)))
-    (if (and (origin? origin)
-             (eqv? (origin-method origin) url-fetch))
-        (filter-map check-source-uri
-                    (origin-uris origin))
-        '())))
-
-(define (check-mirror-url package)
-  "Check whether PACKAGE uses source URLs that should be 'mirror://'."
-  (define (check-mirror-uri uri)                  ;XXX: could be optimized
-    (let loop ((mirrors %mirrors))
-      (match mirrors
-        (()
-         #f)
-        (((mirror-id mirror-urls ...) rest ...)
-         (match (find (cut string-prefix? <> uri) mirror-urls)
-           (#f
-            (loop rest))
-           (prefix
-            (make-warning package
-                          (G_ "URL should be \
-'mirror://~a/~a'")
-                          (list mirror-id
-                                (string-drop uri (string-length prefix)))
-                          #:field 'source)))))))
-
-  (let ((origin (package-source package)))
-    (if (and (origin? origin)
-             (eqv? (origin-method origin) url-fetch))
-        (let ((uris (origin-uris origin)))
-          (filter-map check-mirror-uri uris))
-        '())))
-
-(define* (check-github-url package #:key (timeout 3))
-  "Check whether PACKAGE uses source URLs that redirect to GitHub."
-  (define (follow-redirect url)
-    (let* ((uri      (string->uri url))
-           (port     (guix:open-connection-for-uri uri #:timeout timeout))
-           (response (http-head uri #:port port)))
-      (close-port port)
-      (case (response-code response)
-        ((301 302)
-         (uri->string (assoc-ref (response-headers response) 'location)))
-        (else #f))))
-
-  (define (follow-redirects-to-github uri)
-    (cond
-     ((string-prefix? "https://github.com/" uri) uri)
-     ((string-prefix? "http" uri)
-      (and=> (follow-redirect uri) follow-redirects-to-github))
-     ;; Do not attempt to follow redirects on URIs other than http and https
-     ;; (such as mirror, file)
-     (else #f)))
-
-  (let ((origin (package-source package)))
-    (if (and (origin? origin)
-             (eqv? (origin-method origin) url-fetch))
-        (filter-map
-         (lambda (uri)
-           (and=> (follow-redirects-to-github uri)
-                  (lambda (github-uri)
-                    (if (string=? github-uri uri)
-                        #f
-                        (make-warning
-                         package
-                         (G_ "URL should be '~a'")
-                         (list github-uri)
-                         #:field 'source)))))
-         (origin-uris origin))
-        '())))
-
-(define (check-derivation package)
-  "Emit a warning if we fail to compile PACKAGE to a derivation."
-  (define (try system)
-    (catch #t
-      (lambda ()
-        (guard (c ((store-protocol-error? c)
-                   (make-warning package
-                                 (G_ "failed to create ~a derivation: ~a")
-                                 (list system
-                                       (store-protocol-error-message c))))
-                  ((message-condition? c)
-                   (make-warning package
-                                 (G_ "failed to create ~a derivation: ~a")
-                                 (list system
-                                       (condition-message c)))))
-          (with-store store
-            ;; Disable grafts since it can entail rebuilds.
-            (parameterize ((%graft? #f))
-              (package-derivation store package system #:graft? #f)
-
-              ;; If there's a replacement, make sure we can compute its
-              ;; derivation.
-              (match (package-replacement package)
-                (#f #t)
-                (replacement
-                 (package-derivation store replacement system
-                                     #:graft? #f)))))))
-      (lambda args
-        (make-warning package
-                      (G_ "failed to create ~a derivation: ~s")
-                      (list system args)))))
-
-  (filter lint-warning?
-          (map try (package-supported-systems package))))
-
-(define (check-license package)
-  "Warn about type errors of the 'license' field of PACKAGE."
-  (match (package-license package)
-    ((or (? license?)
-         ((? license?) ...))
-     '())
-    (x
-     (list
-      (make-warning package (G_ "invalid license field")
-                    #:field 'license)))))
-
-(define (call-with-networking-fail-safe message error-value proc)
-  "Call PROC catching any network-related errors.  Upon a networking error,
-display a message including MESSAGE and return ERROR-VALUE."
-  (guard (c ((http-get-error? c)
-             (warning (G_ "~a: HTTP GET error for ~a: ~a (~s)~%")
-                      message
-                      (uri->string (http-get-error-uri c))
-                      (http-get-error-code c)
-                      (http-get-error-reason c))
-             error-value))
-    (catch #t
-      proc
-      (match-lambda*
-        (('getaddrinfo-error errcode)
-         (warning (G_ "~a: host lookup failure: ~a~%")
-                  message
-                  (gai-strerror errcode))
-         error-value)
-        (('tls-certificate-error args ...)
-         (warning (G_ "~a: TLS certificate error: ~a")
-                  message
-                  (tls-certificate-error-string args))
-         error-value)
-        (args
-         (apply throw args))))))
-
-(define-syntax-rule (with-networking-fail-safe message error-value exp ...)
-  (call-with-networking-fail-safe message error-value
-                                  (lambda () exp ...)))
-
-(define (current-vulnerabilities*)
-  "Like 'current-vulnerabilities', but return the empty list upon networking
-or HTTP errors.  This allows network-less operation and makes problems with
-the NIST server non-fatal."
-  (with-networking-fail-safe (G_ "while retrieving CVE vulnerabilities")
-                             '()
-                             (current-vulnerabilities)))
-
-(define package-vulnerabilities
-  (let ((lookup (delay (vulnerabilities->lookup-proc
-                        (current-vulnerabilities*)))))
-    (lambda (package)
-      "Return a list of vulnerabilities affecting PACKAGE."
-      ;; First we retrieve the Common Platform Enumeration (CPE) name and
-      ;; version for PACKAGE, then we can pass them to LOOKUP.
-      (let ((name    (or (assoc-ref (package-properties package)
-                                    'cpe-name)
-                         (package-name package)))
-            (version (or (assoc-ref (package-properties package)
-                                    'cpe-version)
-                         (package-version package))))
-        ((force lookup) name version)))))
-
-(define (check-vulnerabilities package)
-  "Check for known vulnerabilities for PACKAGE."
-  (let ((package (or (package-replacement package) package)))
-    (match (package-vulnerabilities package)
-      (()
-       '())
-      ((vulnerabilities ...)
-       (let* ((patched    (package-patched-vulnerabilities package))
-              (known-safe (or (assq-ref (package-properties package)
-                                        'lint-hidden-cve)
-                              '()))
-              (unpatched (remove (lambda (vuln)
-                                   (let ((id (vulnerability-id vuln)))
-                                     (or (member id patched)
-                                         (member id known-safe))))
-                                 vulnerabilities)))
-         (if (null? unpatched)
-             '()
-             (list
-              (make-warning
-               package
-               (G_ "probably vulnerable to ~a")
-               (list (string-join (map vulnerability-id unpatched)
-                                  ", "))))))))))
-
-(define (check-for-updates package)
-  "Check if there is an update available for PACKAGE."
-  (match (with-networking-fail-safe
-          (G_ "while retrieving upstream info for '~a'")
-          (list (package-name package))
-          #f
-          (package-latest-release* package (force %updaters)))
-    ((? upstream-source? source)
-     (if (version>? (upstream-source-version source)
-                    (package-version package))
-         (list
-          (make-warning package
-                        (G_ "can be upgraded to ~a")
-                        (list (upstream-source-version source))
-                        #:field 'version))
-         '()))
-    (#f '()))) ; cannot find newer upstream release
-
-
-;;;
-;;; Source code formatting.
-;;;
-
-(define (report-tabulations package line line-number)
-  "Warn about tabulations found in LINE."
-  (match (string-index line #\tab)
-    (#f #t)
-    (index
-     (make-warning package
-                   (G_ "tabulation on line ~a, column ~a")
-                   (list line-number index)
-                   #:location
-                   (location (package-file package)
-                             line-number
-                             index)))))
-
-(define (report-trailing-white-space package line line-number)
-  "Warn about trailing white space in LINE."
-  (unless (or (string=? line (string-trim-right line))
-              (string=? line (string #\page)))
-    (make-warning package
-                  (G_ "trailing white space on line ~a")
-                  (list line-number)
-                  #:location
-                  (location (package-file package)
-                            line-number
-                            0))))
-
-(define (report-long-line package line line-number)
-  "Emit a warning if LINE is too long."
-  ;; Note: We don't warn at 80 characters because sometimes hashes and URLs
-  ;; make it hard to fit within that limit and we want to avoid making too
-  ;; much noise.
-  (when (> (string-length line) 90)
-    (make-warning package
-                  (G_ "line ~a is way too long (~a characters)")
-                  (list line-number (string-length line))
-                  #:location
-                  (location (package-file package)
-                            line-number
-                            0))))
-
-(define %hanging-paren-rx
-  (make-regexp "^[[:blank:]]*[()]+[[:blank:]]*$"))
-
-(define (report-lone-parentheses package line line-number)
-  "Emit a warning if LINE contains hanging parentheses."
-  (when (regexp-exec %hanging-paren-rx line)
-    (make-warning package
-                  (G_ "parentheses feel lonely, \
-move to the previous or next line")
-                  (list line-number)
-                  #:location
-                  (location (package-file package)
-                            line-number
-                            0))))
-
-(define %formatting-reporters
-  ;; List of procedures that report formatting issues.  These are not separate
-  ;; checkers because they would need to re-read the file.
-  (list report-tabulations
-        report-trailing-white-space
-        report-long-line
-        report-lone-parentheses))
-
-(define* (report-formatting-issues package file starting-line
-                                   #:key (reporters %formatting-reporters))
-  "Report white-space issues in FILE starting from STARTING-LINE, and report
-them for PACKAGE."
-  (define (sexp-last-line port)
-    ;; Return the last line of the sexp read from PORT or an estimate thereof.
-    (define &failure (list 'failure))
-
-    (let ((start      (ftell port))
-          (start-line (port-line port))
-          (sexp       (catch 'read-error
-                        (lambda () (read port))
-                        (const &failure))))
-      (let ((line (port-line port)))
-        (seek port start SEEK_SET)
-        (set-port-line! port start-line)
-        (if (eq? sexp &failure)
-            (+ start-line 60)                     ;conservative estimate
-            line))))
-
-  (call-with-input-file file
-    (lambda (port)
-      (let loop ((line-number 1)
-                 (last-line #f)
-                 (warnings '()))
-        (let ((line (read-line port)))
-          (if (or (eof-object? line)
-                  (and last-line (> line-number last-line)))
-              warnings
-              (if (and (= line-number starting-line)
-                       (not last-line))
-                  (loop (+ 1 line-number)
-                        (+ 1 (sexp-last-line port))
-                        warnings)
-                  (loop (+ 1 line-number)
-                        last-line
-                        (append
-                         warnings
-                         (if (< line-number starting-line)
-                             '()
-                             (filter
-                              lint-warning?
-                              (map (lambda (report)
-                                     (report package line line-number))
-                                   reporters))))))))))))
-
-(define (check-formatting package)
-  "Check the formatting of the source code of PACKAGE."
-  (let ((location (package-location package)))
-    (if location
-        (and=> (search-path %load-path (location-file location))
-               (lambda (file)
-                 ;; Report issues starting from the line before the 'package'
-                 ;; form, which usually contains the 'define' form.
-                 (report-formatting-issues package file
-                                           (- (location-line location) 1))))
-        '())))
-
-
-;;;
-;;; List of checkers.
-;;;
-
-(define %checkers
-  (list
-   (lint-checker
-     (name        'description)
-     (description "Validate package descriptions")
-     (check       check-description-style))
-   (lint-checker
-     (name        'gnu-description)
-     (description "Validate synopsis & description of GNU packages")
-     (check       check-gnu-synopsis+description))
-   (lint-checker
-     (name        'inputs-should-be-native)
-     (description "Identify inputs that should be native inputs")
-     (check       check-inputs-should-be-native))
-   (lint-checker
-     (name        'inputs-should-not-be-input)
-     (description "Identify inputs that shouldn't be inputs at all")
-     (check       check-inputs-should-not-be-an-input-at-all))
-   (lint-checker
-     (name        'patch-file-names)
-     (description "Validate file names and availability of patches")
-     (check       check-patch-file-names))
-   (lint-checker
-     (name        'home-page)
-     (description "Validate home-page URLs")
-     (check       check-home-page))
-   (lint-checker
-     (name        'license)
-     ;; TRANSLATORS: <license> is the name of a data type and must not be
-     ;; translated.
-     (description "Make sure the 'license' field is a <license> \
-or a list thereof")
-     (check       check-license))
-   (lint-checker
-     (name        'source)
-     (description "Validate source URLs")
-     (check       check-source))
-   (lint-checker
-     (name        'mirror-url)
-     (description "Suggest 'mirror://' URLs")
-     (check       check-mirror-url))
-   (lint-checker
-     (name        'github-url)
-     (description "Suggest GitHub URLs")
-     (check       check-github-url))
-   (lint-checker
-     (name        'source-file-name)
-     (description "Validate file names of sources")
-     (check       check-source-file-name))
-   (lint-checker
-     (name        'source-unstable-tarball)
-     (description "Check for autogenerated tarballs")
-     (check       check-source-unstable-tarball))
-   (lint-checker
-     (name        'derivation)
-     (description "Report failure to compile a package to a derivation")
-     (check       check-derivation))
-   (lint-checker
-     (name        'synopsis)
-     (description "Validate package synopses")
-     (check       check-synopsis-style))
-   (lint-checker
-     (name        'cve)
-     (description "Check the Common Vulnerabilities and Exposures\
- (CVE) database")
-     (check       check-vulnerabilities))
-   (lint-checker
-     (name        'refresh)
-     (description "Check the package for new upstream releases")
-     (check       check-for-updates))
-   (lint-checker
-     (name        'formatting)
-     (description "Look for formatting issues in the source")
-     (check       check-formatting))))
-
 (define* (run-checkers package #:optional (checkers %checkers))
   "Run the given CHECKERS on PACKAGE."
   (let ((tty? (isatty? (current-error-port))))
@@ -1260,6 +68,16 @@ or a list thereof")
       (format (current-error-port) "\x1b[K")
       (force-output (current-error-port)))))
 
+(define (list-checkers-and-exit)
+  ;; Print information about all available checkers and exit.
+  (format #t (G_ "Available checkers:~%"))
+  (for-each (lambda (checker)
+              (format #t "- ~a: ~a~%"
+                      (lint-checker-name checker)
+                      (G_ (lint-checker-description checker))))
+            %checkers)
+  (exit 0))
+
 
 ;;;
 ;;; Command-line options.