15.4.2 Constant aggregates with unconstrained nominal types ¶

In such cases the aggregate itself establishes the subtype, so that associations with others cannot be used. GNAT determines the bounds for the actual subtype of the aggregate, and allocates the aggregate statically as well. No code is generated for the following:

type One_Unc is array (natural range <>) of integer;
Cr_Unc : constant One_Unc := (12,24,36);