From 841d08fe4cbea95da6420f4e27b63461ab816cad Mon Sep 17 00:00:00 2001
From: David Cox <4259949+david-r-cox@users.noreply.github.com>
Date: Tue, 3 Jan 2023 13:08:14 -1000
Subject: [PATCH] Support SWI-Prolog versions > 8.5.2 (#133)

Support SWI-Prolog versions > 8.5.2

After SWI-Prolog 8.5.2, PL_version was renamed to PL_version_info,
causing pyswip to crash when used with SWI-Prolog versions > 8.5.2.
---
 CONTRIBUTORS.txt |  1 +
 pyswip/core.py   | 14 +++++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index 2ed813c..df0553b 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -26,3 +26,4 @@ Guglielmo Gemignani
 Vince Jankovics
 Tobias Grubenmann
 Arvid Norlander
+David Cox
diff --git a/pyswip/core.py b/pyswip/core.py
index 20a4f6a..725d984 100644
--- a/pyswip/core.py
+++ b/pyswip/core.py
@@ -587,16 +587,24 @@ def check_and_call(*args):
 PL_VERSION_VM		=6	# VM signature
 PL_VERSION_BUILT_IN	=7	# Built-in predicate signature
 
+
+# After SWI-Prolog 8.5.2, PL_version was renamed to PL_version_info
+# to avoid a conflict with Perl. For more details, see the following:
+# https://github.com/SWI-Prolog/swipl-devel/issues/900
+# https://github.com/SWI-Prolog/swipl-devel/issues/910
 try:
-    PL_version = _lib.PL_version
+    if _lib.PL_version_info != None:
+        PL_version = _lib.PL_version_info # swi-prolog > 8.5.2
+    else:
+        PL_version = _lib.PL_version # swi-prolog <= 8.5.2
     PL_version.argtypes = [c_int]
     PL_version.restype = c_uint
 
     PL_VERSION = PL_version(PL_VERSION_SYSTEM)
     if PL_VERSION<80200:
-        raise Exception("swi-prolog>= 8.2.0 is required")
+        raise Exception("swi-prolog >= 8.2.0 is required")
 except AttributeError:
-    PL_VERSION=70000  # Best guess. When was PL_version introduced?
+    raise Exception("swi-prolog version number could not be determined")
 
 
 # PySwip constants