maint: fix use of copyright year intervals.

* gnulib: Update.
* bootstrap.conf (gnulib_modules): Update getopt to getopt-gnu
as now recommended in gnulib/NEWS.
* build-aux/update-b4-copyright: Fix.
* cfg.mk (update-copyright-env): Configure update-copyright.
(cherry picked from commit 75ac158b82be1fab5157b140287368165a50ec82)

1 files changed, 17 insertions, 15 deletions

diff --git a/build-aux/update-b4-copyright b/build-aux/update-b4-copyright
index af43407d..30c38013 100755
--- a/build-aux/update-b4-copyright
+++ b/build-aux/update-b4-copyright
@@ -42,7 +42,7 @@ my $old_re = <<'EOF'
   (?:
     ,\s*
     (
-      \[\s* (?:\d{4}(,\s*|-))* (\d{4}) \s*]
+      \[\s* (?:\d{4}(?:,\s*|-))* (\d{4}) \s*]
     )
   )?
   \)
@@ -54,8 +54,7 @@ while (/($old_re)/gx)
     my $start = pos() - length ($1);
     my $b4_copyright_line = $2;
     my $year_lines = $3;
-    my $sep = $4 ? $4 : "";
-    my $final_year = $5;
+    my $final_year = $4;
     $year_lines .= ')';
 
     # If there was a second argument, it contains years, so update them.
@@ -65,18 +64,7 @@ while (/($old_re)/gx)
         if ($final_year != $this_year)
           {
             # Update the year.
-            if ($sep eq '-' && $final_year + 1 == $this_year)
-              {
-                $year_lines =~ s/$final_year/$this_year/;
-              }
-            elsif ($sep ne '-' && $final_year + 1 == $this_year)
-              {
-                $year_lines =~ s/$final_year/$final_year-$this_year/;
-              }
-            else
-              {
-                $year_lines =~ s/$final_year/$final_year, $this_year/;
-              }
+            $year_lines =~ s/$final_year/$final_year, $this_year/;
           }
 
         # Normalize all whitespace.
@@ -85,6 +73,20 @@ while (/($old_re)/gx)
         # Put spaces after commas.
         $year_lines =~ s/, ?/, /g;
 
+        # Compress to intervals.
+        $year_lines =~
+          s/
+            (\d{4})
+            (?:
+              (,\ |-)
+              ((??{
+                if    ($2 eq '-') { '\d{4}'; }
+                elsif (!$3)       { $1 + 1;  }
+                else              { $3 + 1;  }
+              }))
+            )+
+          /$1-$3/gx;
+
         # Format within margin.
         my $year_lines_new;
         my $indent = index ($b4_copyright_line, '[');