Pragma Unimplemented_Unit (GNAT Reference Manual)

### 2.194 Pragma Unimplemented_Unit ¶

Syntax:

    pragma Unimplemented_Unit;

If this pragma occurs in a unit that is processed by the compiler, GNAT aborts with the message `xxx is not supported in this configuration`, where `xxx` is the name of the current compilation unit. This pragma is intended to allow the compiler to handle unimplemented library units in a clean manner.

The abort only happens if code is being generated. Thus you can use specs of unimplemented packages in syntax or semantic checking mode.