How are Ada rep-spec 'use at or 'size clauses translated? (iow. how does a record (or variable) get mapped to an address with correct size).

How are Ada rep-spec 'use at or 'size clauses translated? (iow. how does a record (or variable) get mapped to an address with correct size).

Appropriate padding or packing is specified to ensure the generated C struct matches the specified 'size. For "use at" (i.e. for X'Address use ...) a pointer is used in the C code, with the pointer initialized to the specified address.