Constant aggregates with unconstrained nominal types (GNAT Reference Manual)

#### 16.4.2 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);