Pragma not recognised when wrapped in #ifdef

[Simon Peyton-Jones]

| Perhaps CPP shouldn't be a pragma, just a command-line flag? It seems
| to be the only one that affects/involves preprocessor(s). AFAICT, the
| others all affect the haskell compiler stage.

Yes, it does seem anomalous.  I suppose the motivation is that some modules might need CPP and some not, and it's convenient for the module itself to announce that fact.

Simon