- Care must be taken to handle both the 1.10 rules and the 1.20+ rules. In
1.10, built-in functions cannot be constant expressions.
-- Detect non-void functions that lack a return statement
-
-- Detect return statements with a type not matching the funciton's
- return type.
+- Detect code paths in non-void functions that don't reach a return statement
- Handle over-riding built-in functions
- Is the overload per-compilation unit or per-linked shader?