> This makes sense this we can't gimplify a placeholder expression. So > this seems that when i make a constructor for the QUAL_UNION_TYPE i > must iterate the fields and replace the placeholder_expr to have a > reference to the discriminant via another COMPONENT_REF. Though does > this mean for the constructor i will need to create a temporary to > hold onto it to create another component_ref?
The Ada compiler gets rid of all PLACEHOLDER_EXPRs in CONSTRUCTORs because the subtype of these CONSTRUCTORs is always constrained in Ada parlance, i.e. you know the value of the discriminant since it is assigned in the CONSTRUCTOR, so the gimplifier is indeed presumably not wired to eliminate them on its own. -- Eric Botcazou
