From 91f737e4effa109cb22bc1b2000f457fa1ad88db Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <peter@pmikkelsen.com>
Date: Wed, 7 Jul 2021 15:11:18 +0000
Subject: Fix compare/3 for variables named _. They are never equal

---
 builtins.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/builtins.c b/builtins.c
index 1dede9e..b2c7da6 100644
--- a/builtins.c
+++ b/builtins.c
@@ -247,7 +247,9 @@ compareterms(Term *t1, Term *t2)
 		/* Same type term */
 		switch(t1->tag){
 		case VariableTerm:
-			if(t1->clausenr == t2->clausenr)
+			if(runestrcmp(t1->text, L"_") == 0 && runestrcmp(t2->text, L"_") == 0)
+				result = 1; /* Special case since _ and _ are always different */
+			else if(t1->clausenr == t2->clausenr)
 				result = runestrcmp(t1->text, t2->text);
 			else
 				result = Compare(t1->clausenr, t2->clausenr);
-- 
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