Ada subtypes and base types

[Richard Kenner]

    Just to make sure I've dotted the i's and crossed the t's, this is not
    what's happening when we hang in VRP when compiling a-textio.

    We convert the incoming object from natural___XDLU_0___2147483647
    into its base type, perform the addition in the base type, then
    convert back to XDLU_0_2147483647.

The above is exactly what I thought everybody agrees is and should be
happening, so I'm confused by your "this is not what's happening"
comment above.