[PATCH][RFC] Step 1 to a middle-end type-system

[Eric Botcazou]

>   /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is
> !    explicitly, otherwise return false.
> !    This function implicitly defines the middle-end type system.  The
> !    following invariants shall be fulfilled:
> !
> !      1) type_conversion_needed_p is transitive.
> ! 	If a < b and b < c then a < c.

I don't think this is true, take a = c = int and b = char.  Which would 
suggest that the reverse form useless_type_conversion is probably easier
to deal with, conceptually.

-- 
Eric Botcazou