guid_to_string should be freed.

bindings/guile/gnc-optiondb.i

@@ -1226,9 +1226,10 @@ inline SCM return_scm_value(ValueType value)
                     if (guid_list.empty())
                         return scm_simple_format(SCM_BOOL_F, list_format_str, scm_list_1(no_value));
                     SCM string_list{SCM_EOL};
+                    char guid_str[GUID_ENCODING_LENGTH+1];
                     for(auto guid : guid_list)
                     {
-                        auto guid_str{guid_to_string(&guid)};
+                        guid_to_string_buff (&guid, guid_str);
                         auto guid_scm{scm_from_utf8_string(guid_str)};
                         string_list = scm_cons(guid_scm, string_list);
                     }

libgnucash/backend/sql/gnc-owner-sql.cpp

@@ -225,7 +225,11 @@ GncSqlColumnTableEntryImpl<CT_OWNERREF>::add_to_query(QofIdTypeConst obj_name,
     buf.str("");
     auto guid = qof_instance_get_guid(inst);
     if (guid != nullptr)
-        buf << guid_to_string(guid);
+    {
+        char strbuff[GUID_ENCODING_LENGTH+1];
+        guid_to_string_buff (guid, strbuff);
+        buf << strbuff;
+    }
     else
         buf << "NULL";
     vec.emplace_back(std::make_pair(guid_hdr, quote_string(buf.str())));

libgnucash/engine/gnc-option-impl.cpp

@@ -877,7 +877,12 @@ std::string
 GncOptionAccountSelValue::serialize() const noexcept
 {
     static const std::string no_value{"No Value"};
-    return guid_equal(guid_null(), &m_value) ? no_value : guid_to_string(&m_value);
+    if (guid_equal(guid_null(), &m_value))
+        return no_value;
+
+    gchar strbuff[GUID_ENCODING_LENGTH + 1];
+    guid_to_string_buff (&m_value, strbuff);
+    return strbuff;
 }
 
 bool

libgnucash/engine/gnc-option-impl.hpp

@@ -898,7 +898,9 @@ operator<< <GncOptionAccountListValue>(std::ostream& oss,
             first = false;
         else
             oss << " ";
-        oss << guid_to_string(&value);
+        char strbuff[GUID_ENCODING_LENGTH+1];
+        guid_to_string_buff (&value, strbuff);
+        oss << strbuff;
     }
     return oss;
 }