darcs patch: Add a warning flag for when the Prelude is implicitly ...

[Simon Peyton-Jones]

| > +          <option>-fno-implicit-prelude</option> or a
| > +          <literal>LANGUAGE NoImplicitPrelude</literal> pragma).</para>
| >
| > Have you actually altered the LANGUAGE pragma processing?
|
| No, it's an existing LANGUAGE pragma (in fact I use it in one of the
| test cases).

Ah yes, my mistake. I was confusing the existing >-fno-implicit-prelude with your new warning flag.

| > Secondly, this flag should probably *not* be switched on by -Wall.
| > Some warning flags are not: see using.xml line 851.  I suggest
| > you put your new flag in this cateogory, and figure out where to
| > change the compiler's code to make that so.
|
| It turned out that although the documentation, which I changed,
| describes -Wall by subtractions from all documented warnings, the code
| describes -Wall as additions to -W, which is described as additions to
| the default warning flags. So I didn't need to change anything there
| (and a manual test verifies that -Wall doesn't cause this warning where
| - -fwarn-implicit-prelude does).

OK.  And indeed in the docs you have it right.

I'll commit then.  Thanks

Simon