Subject: Fix GDBM_File to compile with version 1.20 and earlier
From: Sergey Poznyakoff <[email-masked]>
Date: Wed, 23 Jun 2021 10:26:50 +0300

* ext/GDBM_File/GDBM_File.xs (ITEM_NOT_FOUND): Define conditionally,
depending on the GDBM_VERSION_MAJOR and GDBM_VERSION_MINOR.
Don't assume GDBM_ITEM_NOT_FOUND is a define (it isn't since
gdbm commit d3e27957).

Origin: backport, https://github.com/Perl/perl5/pull/18924/commits/aacd2398e766500cb5d83c4d76b642fcf31d997a
Bug: https://github.com/Perl/perl5/issues/18915
Bug-Debian: https://bugs.debian.org/993514
---
 ext/GDBM_File/GDBM_File.xs | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/ext/GDBM_File/GDBM_File.xs b/ext/GDBM_File/GDBM_File.xs
index cd0bb6f..494c288 100644
--- a/ext/GDBM_File/GDBM_File.xs
+++ b/ext/GDBM_File/GDBM_File.xs
@@ -145,14 +145,13 @@ output_datum(pTHX_ SV *arg, char *str, int size)
 #define gdbm_setopt(db,optflag,optval,optlen) not_here("gdbm_setopt")
 #endif
 
-#ifndef GDBM_ITEM_NOT_FOUND
-# define GDBM_ITEM_NOT_FOUND GDBM_NO_ERROR
-#endif
-
+#if GDBM_VERSION_MAJOR == 1 && GDBM_VERSION_MINOR < 13        
 /* Prior to 1.13, gdbm_fetch family functions set gdbm_errno to GDBM_NO_ERROR
    if the requested key did not exist */
-#define ITEM_NOT_FOUND()                                                \
-    (gdbm_errno == GDBM_ITEM_NOT_FOUND || gdbm_errno == GDBM_NO_ERROR)
+# define ITEM_NOT_FOUND()  (gdbm_errno == GDBM_NO_ERROR)
+#else
+# define ITEM_NOT_FOUND()  (gdbm_errno == GDBM_ITEM_NOT_FOUND)
+#endif
 
 #define CHECKDB(db) do {                        \
     if (!db->dbp) {                             \