ui: Support Texinfo markup in package synopses.

* guix/ui.scm (package-field-string): New procedure.
(package-description-string): Use it.
(package-synopsis-string): New procedure.
(package->recutils): Use it.
* guix/scripts/lint.scm (check-synopsis-style)[check-texinfo-markup]:
New procedure.  Use it in checks.
* tests/lint.scm: Test it.
* gnu/packages/perl.scm (perl-try-tiny)[synopsis]: Adjust for the
Texinfo markup.

gnu/packages/perl.scm

@@ -7684,7 +7684,7 @@ (define-public perl-try-tiny
          "068vdbpacfawc3lkfs0b82xxl27h3l0gj14iada3vlwk8rps9yv0"))))
     (build-system perl-build-system)
     (home-page "http://search.cpan.org/dist/Try-Tiny")
-    (synopsis "Minimal try/catch with proper preservation of $@")
+    (synopsis "Minimal try/catch with proper preservation of $@@")
     (description "This module provides bare bones try/catch/finally statements
 that are designed to minimize common mistakes with eval blocks, and nothing
 else.")

guix/scripts/lint.scm

@@ -5,6 +5,7 @@
 ;;; Copyright © 2015, 2016 Mathieu Lirzin <mthl@gnu.org>
 ;;; Copyright © 2016 Danny Milosavljevic <dannym+a@scratchpost.org>
 ;;; Copyright © 2016 Hartmut Goebel <h.goebel@crazy-compilers.com>
+;;; Copyright © 2017 Alex Kost <alezost@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -347,10 +348,25 @@ (define (check-start-with-package-name synopsis)
                     (_ "synopsis should not start with the package name")
                     '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)
+        (emit-warning package
+                      (_ "Texinfo markup in synopsis is invalid")
+                      'synopsis)
+        #f)))
+
   (define checks
-    (list check-not-empty check-proper-start check-final-period
-          check-start-article check-start-with-package-name
-          check-synopsis-length))
+    (list check-not-empty
+          check-proper-start
+          check-final-period
+          check-start-article
+          check-start-with-package-name
+          check-synopsis-length
+          check-texinfo-markup))
 
   (match (package-synopsis package)
     ((? string? synopsis)

guix/ui.scm

@@ -4,7 +4,7 @@
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2014 Cyril Roelandt <tipecaml@gmail.com>
 ;;; Copyright © 2014 Cyrill Schenkel <cyrill.schenkel@gmail.com>
-;;; Copyright © 2014, 2015 Alex Kost <alezost@gmail.com>
+;;; Copyright © 2014, 2015, 2017 Alex Kost <alezost@gmail.com>
 ;;; Copyright © 2015 David Thompson <davet@gnu.org>
 ;;; Copyright © 2015, 2016 Mathieu Lirzin <mthl@gnu.org>
 ;;; Copyright © 2016 Roel Janssen <roel@gnu.org>
@@ -81,6 +81,7 @@ (define-module (guix ui)
             fill-paragraph
             texi->plain-text
             package-description-string
+            package-synopsis-string
             string->recutils
             package->recutils
             package-specification->name+version+output
@@ -848,10 +849,18 @@ (define (texi->plain-text str)
   (with-fluids ((%default-port-encoding "UTF-8"))
     (stexi->plain-text (texi-fragment->stexi str))))
 
+(define (package-field-string package field-accessor)
+  "Return a plain-text representation of PACKAGE field."
+  (and=> (field-accessor package)
+         (compose texi->plain-text P_)))
+
 (define (package-description-string package)
   "Return a plain-text representation of PACKAGE description field."
-  (and=> (package-description package)
-         (compose texi->plain-text P_)))
+  (package-field-string package package-description))
+
+(define (package-synopsis-string package)
+  "Return a plain-text representation of PACKAGE synopsis field."
+  (package-field-string package package-synopsis))
 
 (define (string->recutils str)
   "Return a version of STR where newlines have been replaced by newlines
@@ -914,7 +923,7 @@ (define (package<? p1 p2)
           (string-map (match-lambda
                        (#\newline #\space)
                        (chr       chr))
-                      (or (and=> (package-synopsis p) P_)
+                      (or (and=> (package-synopsis-string p) P_)
                           "")))
   (format port "~a~2%"
           (string->recutils

tests/lint.scm

@@ -4,6 +4,7 @@
 ;;; Copyright © 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015, 2016 Mathieu Lirzin <mthl@gnu.org>
 ;;; Copyright © 2016 Hartmut Goebel <h.goebel@crazy-compilers.com>
+;;; Copyright © 2017 Alex Kost <alezost@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -167,6 +168,13 @@ (define-syntax-rule (with-warnings body ...)
                         (check-synopsis-style pkg)))
                     "synopsis should not be empty")))
 
+(test-assert "synopsis: valid Texinfo markup"
+  (->bool
+   (string-contains
+    (with-warnings
+      (check-synopsis-style (dummy-package "x" (synopsis "Bad $@ texinfo"))))
+    "Texinfo markup in synopsis is invalid")))
+
 (test-assert "synopsis: does not start with an upper-case letter"
   (->bool
    (string-contains (with-warnings