RM 2 8 16 Pragmas (GNAT Reference Manual)

### 6.4 RM 2.8(16): Pragmas ¶

> “Normally, implementation-defined pragmas should have no semantic effect for error-free programs; that is, if the implementation-defined pragmas are removed from a working program, the program should still be legal, and should still have the same semantics.”

The following implementation defined pragmas are exceptions to this rule:

Pragma | Explanation
--- | ---
‘Abort_Defer’ | Affects semantics
‘Ada_83’ | Affects legality
‘Assert’ | Affects semantics
‘CPP_Class’ | Affects semantics
‘CPP_Constructor’ | Affects semantics
‘Debug’ | Affects semantics
‘Interface_Name’ | Affects semantics
‘Machine_Attribute’ | Affects semantics
‘Unimplemented_Unit’ | Affects legality
‘Unchecked_Union’ | Affects semantics

In each of the above cases, it is essential to the purpose of the pragma that this advice not be followed. For details see Implementation Defined Pragmas.