“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.