From e56d717d8a23c48e4ab27b6bd6815c50dc3a378a Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Mon, 13 Apr 2020 19:54:09 -0400
Subject: [PATCH] Silence Perl warning
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Now that warnings are enabled across the board, this code that tries to
print an undef variable emits one.  Silently printing the empty string
achieves the previous behavior.

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Discussion: https://postgr.es/m/E1jO1VT-0008Qk-TM@gemulon.postgresql.org
---
 doc/src/sgml/mk_feature_tables.pl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/mk_feature_tables.pl b/doc/src/sgml/mk_feature_tables.pl
index ee158cb1969..a9dfebfbb31 100644
--- a/doc/src/sgml/mk_feature_tables.pl
+++ b/doc/src/sgml/mk_feature_tables.pl
@@ -54,7 +54,9 @@ while (<$feat>)
 	{
 		print "  <entry>$feature_id</entry>\n";
 	}
-	print "  <entry>" . $feature_packages{$feature_id} . "</entry>\n";
+	print "  <entry>",
+		  defined($feature_packages{$feature_id}) ? $feature_packages{$feature_id} : "",
+		  "</entry>\n";
 	if ($subfeature_id)
 	{
 		print "  <entry>$subfeature_name</entry>\n";
-- 
2.39.5