ghci 7.4.1 no longer loading .o files?

[Evan Laforge]

On Mon, Feb 20, 2012 at 1:14 AM, Eugene Crosser <crosser at average.org> wrote:
> On 02/20/2012 10:46 AM, Evan Laforge wrote:
>> Is there something that changed in 7.4.1 that would cause it to decide
>> to interpret .hs files instead of loading their .o files?  E.g.:
>
> I don't *know* but could this have anything to do with this?
>
> http://hackage.haskell.org/trac/ghc/ticket/5878

Indeed it was, I initially thought it wasn't because I wasn't using
flags for either, but then I remember ghci also picks up flags from
~/.ghci.  Turns out I was using -fno-monomorphism-restriction because
that's convenient for ghci, but not compiling with that.

I guess in the case where an extension changes the meaning of existing
code it should be included in the fingerprint and make the .o not
load.  But my impression is that most ExtensionFlags let compile code
that wouldn't compile without the flag.  So shouldn't it be safe to
exclude them from the fingerprint?

Either way, it's a bit confusing when .ghci is slipping in flags that
are handy for testing, because there's nothing that tells you *why*
ghci won't load a particular .o file.