build: work when perl is installed but not in /usr/bin/perl

Also support building on systems without perl and when cross-compiling.
* configure.ac (AC_ARG_ENABLE [bold-man-page-references]): New
configure-time option, using code copied from coreutils.
(BUILD_MAN_PAGE, BUILD_DUMMY_MAN_PAGE): Remove definitions.
(HAVE_PERL): Remove bogus conditional.
* doc/dummy-man: New file, from coreutils, with slight adapation.
* build-aux/help2man: Update from coreutils.
* doc/local.mk (EXTRA_DIST): Distribute dummy-man.
(run_help2man): New variable.
(doc/sed.1): Use it rather than simply invoking help2man.
Simplify to use only one copy of this rule, now that run_help2man
works both with and without perl and when cross-compiling.
Move the --name=... string argument into...
* doc/sed.x: ... here. Also make the "Synopsis" appear in generated file.
In https://lists.gnu.org/r/sed-devel/2022-10/msg00005.html,
Bruno Haible reported build failure with perl in a different
location and (in another report) another failure with no perl at all.

5 files changed, 138 insertions, 53 deletions

diff --git a/build-aux/help2man b/build-aux/help2man
index 67452e2..581f69d 100755
--- a/build-aux/help2man
+++ b/build-aux/help2man
@@ -1,7 +1,9 @@
 #!/usr/bin/perl -w
 
 # Generate a short man page from --help and --version output.
-# Copyright (C) 1997-2022 Free Software Foundation, Inc.
+# Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2009,
+# 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2020, 2021 Free Software
+# Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -27,7 +29,7 @@ use Text::Tabs qw(expand);
 use POSIX qw(strftime setlocale LC_ALL);
 
 my $this_program = 'help2man';
-my $this_version = '1.47.3';
+my $this_version = '1.48.5';
 
 sub _ { $_[0] }
 sub configure_locale
@@ -51,8 +53,9 @@ sub fix_italic_spacing;
 my $version_info = enc_user sprintf _(<<'EOT'), $this_program, $this_version;
 GNU %s %s
 
-Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2009, 2010,
-2011, 2012, 2013, 2014, 2015 Free Software Foundation, Inc.
+Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2009,
+2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2020, 2021 Free Software
+Foundation, Inc.
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
@@ -75,6 +78,7 @@ Usage: %s [OPTION]... EXECUTABLE
  -p, --info-page=TEXT    name of Texinfo manual
  -N, --no-info           suppress pointer to Texinfo manual
  -l, --libtool           exclude the `lt-' from the program name
+ -b, --bold-refs         apply bold style to references
      --help              print this help, then exit
      --version           print version number, then exit
 
@@ -96,7 +100,7 @@ my $help_option = '--help';
 my $version_option = '--version';
 my $discard_stderr = 1;
 my ($opt_name, @opt_include, $opt_output, $opt_info, $opt_no_info, $opt_libtool,
-    $version_text);
+    $opt_bold_refs, $version_text);
 
 my %opt_def = (
     'n|name=s'		 => \$opt_name,
@@ -110,6 +114,7 @@ my %opt_def = (
     'p|info-page=s'	 => \$opt_info,
     'N|no-info'		 => \$opt_no_info,
     'l|libtool'		 => \$opt_libtool,
+    'b|bold-refs'	 => \$opt_bold_refs,
     'help'		 => sub { print $help_info; exit },
     'version'		 => sub { print $version_info; exit },
     'h|help-option=s'	 => \$help_option,
@@ -247,7 +252,7 @@ my $help_text   = get_option_value $ARGV[0], $help_option;
 $version_text ||= get_option_value $ARGV[0], $version_option;
 
 # By default the generated manual pages will include the current date.  This may
-# however be overriden by setting the environment variable $SOURCE_DATE_EPOCH
+# however be overridden by setting the environment variable $SOURCE_DATE_EPOCH
 # to an integer value of the seconds since the UNIX epoch.  This is primarily
 # intended to support reproducible builds (wiki.debian.org/ReproducibleBuilds)
 # and will additionally ensure that the output date string is UTC.
@@ -282,21 +287,23 @@ if ($opt_output)
 #   <version>
 #   <program> <version>
 #   {GNU,Free} <program> <version>
-#   <program> ({GNU,Free} <package>) <version>
-#   <program> - {GNU,Free} <package> <version>
+#   <program> ({GNU,Free,} <package>) <version>
+#   <program> - {GNU,Free,} <package> <version>
+#   <program> - {GNU,Free,} <package> - <version>
 #
 # and separated from any copyright/author details by a blank line.
 
 ($_, $version_text) = ((split /\n+/, $version_text, 2), '');
 
-if (/^(\S+) +\(((?:GNU|Free) +[^)]+)\) +(.*)/ or
-    /^(\S+) +- *((?:GNU|Free) +\S+) +(.*)/)
+if (/^(\S+) +\(((?:(?:GNU|Free) +)?[^)]+)\) +(\S.*)$/ or
+    /^(\S+) +- +((?:(?:GNU|Free) +)?\S.*) +- +(\S.*)$/ or
+    /^(\S+) +- +((?:(?:GNU|Free) +)?\S+) +(\S.*)$/)
 {
     $program = program_basename $1;
     $package = $2;
     $version = $3;
 }
-elsif (/^((?:GNU|Free) +)?(\S+) +(.*)/)
+elsif (/^((?:GNU|Free) +)?(\S+) +(\S.*)$/)
 {
     $program = program_basename $2;
     $package = $1 ? "$1$program" : $program;
@@ -336,7 +343,7 @@ for ($replace{_('NAME')} || ($include{_('NAME')} ||= ''))
 my $PROGRAM = uc $program;
 
 # Set default page head/footers
-$source ||= "$program $version";
+$source ||= "$package $version";
 unless ($manual)
 {
     for ($section)
@@ -709,6 +716,13 @@ for my $sect (@pre, (grep !$filter{$_}, @sections), @post)
 
 	for ($include{$sect})
 	{
+            # Add bold style around referenced pages.
+            if ($opt_bold_refs)
+            {
+                # This will ignore entries already marked up (with \)
+                s/(^|\s|,)([\[\w\x83]+)\(([1-9][[:lower:]]?)\)/$1\\fB$2\\fP($3)/g;
+            }
+
 	    # Replace leading dot, apostrophe, backslash and hyphen
 	    # tokens.
 	    s/\x80/\\&./g;
diff --git a/configure.ac b/configure.ac
index 62aad18..1f6ff5c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,11 +36,7 @@ gl_DISABLE_THREADS
 AC_DEFINE([GNULIB_NO_VLA], [1], [Define to 1 to disable use of VLAs])
 
 # The test suite needs to know if we have a working perl.
-# FIXME: this is suboptimal.  Ideally, we would be able to call gl_PERL
-# with an ACTION-IF-NOT-FOUND argument ...
-cu_have_perl=yes
-case $PERL in *"/missing "*) cu_have_perl=no;; esac
-AM_CONDITIONAL([HAVE_PERL], [test $cu_have_perl = yes])
+AM_CONDITIONAL([HAVE_PERL], [test "$gl_cv_prog_perl" != no])
 
 # gl_GCC_VERSION_IFELSE([major], [minor], [run-if-found], [run-if-not-found])
 # ------------------------------------------------
@@ -289,29 +285,25 @@ if test "$gl_gcc_warnings" = yes; then
   AC_SUBST([GNULIB_TEST_WARN_CFLAGS])
 fi
 
+AC_ARG_ENABLE([bold-man-page-references],
+  [AS_HELP_STRING([--disable-bold-man-page-references],
+     [When generating man pages, do not apply bold style around any
+      references like name(1) etc.])],
+  [gl_bold_manpages=yes ;
+   case $enableval in
+     no|yes) gl_bold_manpages=$enableval ;;
+     *)      AC_MSG_ERROR([bad value $enableval for bold-man-page-references.
+                           Options are: yes, no.]) ;;
+   esac],
+  [gl_bold_manpages=yes]
+)
+AM_CONDITIONAL([BOLD_MAN_REFS], [test "$gl_bold_manpages" != no])
+
 AM_CONDITIONAL([CROSS_COMPILING], [test "$cross_compiling" = yes])
 
 # Perl is needed for help2man
 AC_PATH_PROG([PERL], [perl])
 
-# Can the man page be built?
-# Perl needed for help2man, executing sed needed for 'sed --help'
-can_rebuild_man_page=no
-test -n "$PERL" && \
-  test "$cross_compiling" != yes && \
-  can_rebuild_man_page=yes
-
-# Build the man page when
-# building from git and rebuilding is possible.
-AM_CONDITIONAL([BUILD_MAN_PAGE],
- [test "$can_rebuild_man_page" = yes])
-
-# Create a stub man page instead of failing when
-# building from git and rebuilding is not possible.
-AM_CONDITIONAL([BUILD_DUMMY_MAN_PAGE],
- [test "$can_rebuild_man_page" = no])
-
-
 # This is needed when building outside the source dir
 # with --disable-dependency-tracking, see https://bugs.gnu.org/25371
 AS_MKDIR_P([lib])
diff --git a/doc/dummy-man b/doc/dummy-man
new file mode 100755
index 0000000..25bde40
--- /dev/null
+++ b/doc/dummy-man
@@ -0,0 +1,73 @@
+#!/bin/sh
+# Poor man's placeholder for help2man invocation on systems lacking perl,
+# or when cross compiling.
+# It just copies the distributed man pages.
+
+set -e; set -u
+
+fatal_ ()
+{
+  printf '%s: %s\n' "$0" "$*" >&2
+  exit 1
+}
+
+basename_ ()
+{
+  printf '%s\n' "$1" | sed 's,.*/,,'
+}
+
+output=
+source="GNU sed"
+while test $# -gt 0; do
+  case $1 in
+    # Help2man options we recognize and handle.
+    --output=*) output=`expr x"$1" : x'--output=\(.*\)'`;;
+    --output) shift; output=$1;;
+    --include=*) include=`expr x"$1" : x'--include=\(.*\)'`;;
+    --include) shift; include=$1;;
+    --source=*) source=`expr x"$1" : x'--source=\(.*\)'`;;
+    --source) shift; source=$1;;
+    # Recognize (as no-op) other help2man options that might be used
+    # in the makefile.
+    --info-page=*);;
+    -*) fatal_ "invalid or unrecognized help2man option '$1'";;
+    --) shift; break;;
+     *) break;;
+  esac
+  shift
+done
+
+test $# -gt 0 || fatal_ "missing argument"
+test $# -le 1 || fatal_ "too many non-option arguments"
+
+dist_man=$(printf '%s\n' "$include" | sed 's/\.x$/.1/')
+test -f "$dist_man" && cp "$dist_man" "$output" && exit || :
+
+baseout=`basename_ "$output"`
+sed 's/^/WARNING: /' >&2 <<END
+Did not generate or find default '$baseout' man page.
+Creating a stub man page instead.
+END
+
+progname=`basename_ "$1"`
+bs='\'
+
+cat >"$output" <<END
+.TH "$progname" 1 "$source" "User Commands"
+.SH NAME
+$progname $bs- stream editor for filtering and transforming text
+.SH DESCRIPTION
+.B OOPS!
+We were unable to create a proper manual page for
+.B $progname.
+For concise option descriptions, run
+.IP
+.B env $progname --help
+.PP
+The full documentation for
+.B $progname
+is maintained as a Texinfo manual, which should be accessible
+on your system via the command
+.IP
+.B info sed invoking
+END
diff --git a/doc/local.mk b/doc/local.mk
index 8433003..7b6f397 100644
--- a/doc/local.mk
+++ b/doc/local.mk
@@ -19,26 +19,32 @@ dist_man_MANS = doc/sed.1
 dist_noinst_DATA = doc/sed.x doc/sed-dummy.1
 HELP2MAN = $(top_srcdir)/build-aux/help2man
 SEDBIN = sed/sed
+EXTRA_DIST += doc/dummy-man
 
 AM_MAKEINFOHTMLFLAGS = --no-split
 
-if BUILD_MAN_PAGE
+## Use the distributed man pages if cross compiling or lack perl
+if CROSS_COMPILING
+run_help2man = $(SHELL) $(srcdir)/doc/dummy-man
+else
+## Graceful degradation for systems lacking perl.
+if HAVE_PERL
+if BOLD_MAN_REFS
+help2man_OPTS=--bold-refs
+endif
+run_help2man = $(PERL) -- $(HELP2MAN) $(help2man_OPTS)
+else
+run_help2man = $(SHELL) $(srcdir)/doc/dummy-man
+endif
+endif
+
 doc/sed.1: sed/sed$(EXEEXT) .version $(srcdir)/doc/sed.x
 	$(AM_V_GEN)$(MKDIR_P) doc
 	$(AM_V_at)rm -rf $@ $@-t
-	$(AM_V_at)$(HELP2MAN)						\
-	    --name 'stream editor for filtering and transforming text'	\
-	    -p sed --include $(srcdir)/doc/sed.x			\
-	    -o $@-t $(SEDBIN)						\
+	$(AM_V_at)$(run_help2man)					\
+	    --info-page=sed						\
+	    --include $(srcdir)/doc/sed.x				\
+	    --output=$@-t						\
+	    $(SEDBIN)							\
 	  && chmod a-w $@-t						\
 	  && mv $@-t $@
-else !BUILD_MAN_PAGE
-
-if BUILD_DUMMY_MAN_PAGE
-doc/sed.1: doc/sed-dummy.1
-	$(AM_V_at)$(SED) 's/VERSION/$(PACKAGE_VERSION)/' $< > $@-t	\
-	  && chmod a-w $@-t						\
-	  && mv $@-t $@
-endif BUILD_DUMMY_MAN_PAGE
-
-endif !BUILD_MAN_PAGE
diff --git a/doc/sed.x b/doc/sed.x
index 1059382..5e060a2 100644
--- a/doc/sed.x
+++ b/doc/sed.x
@@ -1,6 +1,6 @@
-.SH NAME
-sed \- a Stream EDitor
-.SH SYNOPSIS
+[NAME]
+sed \- stream editor for filtering and transforming text
+[SYNOPSIS]
 .nf
 sed [-V] [--version] [--help] [-n] [--quiet] [--silent]
     [-l N] [--line-length=N] [-u] [--unbuffered]