From 2d1f182c496ba09dbfa8604f7b072f983fef14eb Mon Sep 17 00:00:00 2001
From: Markus Triska <triska@metalevel.at>
Date: Mon, 8 Nov 2021 22:10:14 +0100
Subject: [PATCH] FIXED: instantiation errors for type(Var) in open/4 options

This addresses #1030.
---
 src/lib/builtins.pl | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/lib/builtins.pl b/src/lib/builtins.pl
index 3c9c27a1..1a92acf9 100644
--- a/src/lib/builtins.pl
+++ b/src/lib/builtins.pl
@@ -1429,7 +1429,10 @@ parse_stream_options(Options, OptionValues, Stub) :-
 
 
 parse_stream_options_(type(Type), type-Type) :-
-    (  nonvar(Type), lists:member(Type, [text, binary]), !, true
+    (  var(Type) ->
+       throw(error(instantiation_error, open/4)) % 8.1.3 7)
+    ;
+       lists:member(Type, [text, binary]) -> true
     ;
        throw(error(domain_error(stream_option, type(Type)), _))
     ).
-- 
2.54.0