ghc --make feature request

[Simon Marlow]

> "Simon Marlow" <simonmar@microsoft.com> writes:
>=20
> > GHC actually has rather sophisticated recompilation checking which
> > goes beyond just checking whether the interface changed - it keeps
> > version information for each entity exported by a module and only
> > recompiles if any of the entities actually used by the module have
> > changed (this is described in the user's guide under the section on
> > recompilation checking).
>=20
> I've seen unexpected compiles using ghc --make.  I've got a system
> with modules A, B, and C; A depends on B and B depends on C.  I've
> seen the following sequence of events:
>=20
> I change C
> ghc --make A compiles C, B, and A
> I change A
> ghc --make A skips C and compiles B and A
>=20
> I don't know of any reason why it would have compiled B in the second
> case.
>=20
> If this is not a known bug, I can try to reproduce it and submit a
> formal bug report.

It's not a known bug, although we have encountered problems of this kind =
in the past.  Thanks for the report, we'll look into it.

Cheers,
	Simon