From 6465569a518aa2bf3ce93e5934a58eec2e6a69b1 Mon Sep 17 00:00:00 2001
From: David Kastrup <dak@gnu.org>
Date: Tue, 3 May 2016 20:39:48 +0200
Subject: [PATCH] Issue 4841: Let Scheme_hash_table::get return SCM_UNDEFINED
 for unknown keys

---
 lily/scm-hash.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lily/scm-hash.cc b/lily/scm-hash.cc
index 3eb40ada7b..97af8f6cd5 100644
--- a/lily/scm-hash.cc
+++ b/lily/scm-hash.cc
@@ -69,9 +69,13 @@ Scheme_hash_table::set (SCM k, SCM v)
 SCM
 Scheme_hash_table::get (SCM k) const
 {
-  /* SCM_UNSPECIFIED will stick out like a sore thumb, hopefully.
+  /* SCM_UNDEFINED is the default for unset elements, but
+     scm_hashq_ref cannot return it, so we do it a bit more awkwardly.
   */
-  return scm_hashq_ref (hash_tab (), k, SCM_UNSPECIFIED);
+  SCM handle = scm_hashq_get_handle (hash_tab (), k);
+  if (scm_is_pair (handle))
+    return scm_cdr (handle);
+  return SCM_UNDEFINED;
 }
 
 void
-- 
2.39.5