Adding upstream version 3.1.0+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tests/yanglint/modules/modextleafref.yang

@@ -0,0 +1,24 @@
+module modextleafref {
+  namespace "urn:yanglint:modextleafref";
+  prefix mel;
+
+  list ls {
+    key k;
+    leaf k {
+      type string;
+    }
+    leaf lf {
+      type uint8;
+    }
+  }
+  leaf lfr {
+    type leafref {
+      path "../ls/k";
+    }
+  }
+  leaf lfrderef {
+    type leafref {
+      path "deref(../lfr)/../lf";
+    }
+  }
+}