Update caldav_functions.sql for Postgresql 10

From version 10, Postgresql does not allow set-returning functions in
CASE statements. As we're using the functions recursively, we cannot
use LATERAL as suggested in the error message, but we can switch the
condition inside-out with only a limited amount of repetition.

dba/caldav_functions.sql

@@ -897,21 +897,37 @@ LANGUAGE plpgsql IMMUTABLE STRICT;
 
 -- Expanded group memberships out to some depth
 CREATE or REPLACE FUNCTION expand_memberships( INT8, INT ) RETURNS SETOF INT8 AS $$
+BEGIN
+  IF $2 > 0 THEN
+    RETURN QUERY
       SELECT group_id FROM group_member WHERE member_id = $1
         UNION
-  SELECT expanded.g_id FROM (SELECT CASE WHEN $2 > 0 THEN expand_memberships( group_id, $2 - 1) END AS g_id
+      SELECT expanded.g_id FROM (SELECT expand_memberships( group_id, $2 - 1) AS g_id
                                  FROM group_member WHERE member_id = $1) AS expanded
                             WHERE expanded.g_id IS NOT NULL;
-$$ LANGUAGE sql STABLE STRICT;
+  ELSE
+    RETURN QUERY
+      SELECT group_id FROM group_member WHERE member_id = $1;
+  END IF;
+END
+$$ LANGUAGE plpgsql IMMUTABLE STRICT;
 
 -- Expanded group members out to some depth
 CREATE or REPLACE FUNCTION expand_members( INT8, INT ) RETURNS SETOF INT8 AS $$
+BEGIN
+  IF $2 > 0 THEN
+    RETURN QUERY
       SELECT member_id FROM group_member WHERE group_id = $1
         UNION
-  SELECT expanded.m_id FROM (SELECT CASE WHEN $2 > 0 THEN expand_members( member_id, $2 - 1) END AS m_id
+      SELECT expanded.m_id FROM (SELECT expand_members( member_id, $2 - 1) AS m_id
                                  FROM group_member WHERE group_id = $1) AS expanded
                             WHERE expanded.m_id IS NOT NULL;
-$$ LANGUAGE sql STABLE STRICT;
+  ELSE
+    RETURN QUERY
+      SELECT member_id FROM group_member WHERE group_id = $1;
+  END IF;
+END
+$$ LANGUAGE plpgsql IMMUTABLE STRICT;
 
 
 

testing/tests/regression-suite/Really-Upgrade-Database.result

@@ -1,4 +1,4 @@
-The database is version 9.6 currently at revision 1.3.2.
+The database is version 10.0 currently at revision 1.3.2.
 No patches were applied.
 Supported locales updated.
 Updated view: dav_principal.sql applied.