From a8c5a4f93f73f7d23336e6dbdea8b262a24535ff Mon Sep 17 00:00:00 2001
From: Krasimir Angelov <kr.angelov@gmail.com>
Date: Thu, 14 Mar 2024 18:08:22 +0100
Subject: [PATCH] properly skip unknown languages in pgf_write_pgf

---
 src/runtime/c/pgf/writer.cxx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/runtime/c/pgf/writer.cxx b/src/runtime/c/pgf/writer.cxx
index b47dc9d35..3c210793f 100644
--- a/src/runtime/c/pgf/writer.cxx
+++ b/src/runtime/c/pgf/writer.cxx
@@ -455,7 +455,10 @@ void PgfWriter::write_pgf(ref<PgfPGF> pgf)
         size_t len = 0;
         PgfText** p = langs;
         while (*p) {
-            len++; p++;
+            if (namespace_lookup(pgf->concretes, *p) != 0) {
+                len++;
+            }
+            p++;
         }
         write_len(len);
     }