+#!perl -w
+use v5.10.1;
+my $v = $ENV{VERSION} // die 'VERSION unset';
+my $f = './lib/PublicInbox.pm';
+if (-d ($ENV{GIT_DIR} // '.git') || -f '.git') {
+ chomp(my $gv = `git describe --match "v[0-9]*" HEAD`);
+ if ($? == 0) {
+ substr($gv, 0, 1, ''); # remove "v"
+ system(qw(git update-index -q --refresh));
+ if (my @n = `git diff-index --name-only HEAD --`) {
+ $gv .= '-dirty';
+ }
+ $v = $gv;
+ }
+}
+$v =~ tr/-/./;
+if (-f $f && do $f && (eval('$PublicInbox::VERSION') // 'undef') eq $v) {
+ exit
+}
+my $tmp = "$f.tmp.$$";
+open my $fh, '>', $tmp or die "open($tmp): $!";
+print $fh <<EOM or die "print($tmp): $!";
+# this file is generated by $0
+package PublicInbox;
+our \$VERSION = '$v';
+1;
+EOM
+close $fh or die "close($tmp): $!";
+rename($tmp, $f) or die "rename($tmp, $f): $!";