head aches in parser/Parser.hs

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Tue Aug 5 15:12:46 EDT 2008

On Tue, 2008-08-05 at 22:11 +1000, Roman Leshchinskiy wrote:
> On 05/08/2008, at 21:15, Duncan Coutts wrote:
> > It knows that .y can be pre-processed to .hs so if it finds both .hs
> > and .y then it knows that .y is the ultimate source file and
> > pre-processes that.
> >
> > Do you think this is the wrong behaviour or are you observing  
> > different
> > behaviour?
> I think I'm observing a different behaviour. I don't think a Parser.hs  
> left over from a previous build would have affected the build with the  
> behaviour you describe.

I suspect it might be different behaviour between the cabal build and
the makefile that the ghc build system generates. I just tried it with a
simple test case and with cabal build it works how I expected. For the
makefiles I defer to Ian and Simon.

> Out of idle curiousity, what happens if Cabal finds both Foo.y and  
> Foo.x? Is all this documented somewhere? I couldn't find anything in  
> the Cabal docs but maybe I just looked in the wrong place.

That's essentially undefined. It'll depend on the order in which we
check the .x and .y suffix rules.

That's the kind of ambiguous case I was suggesting we should warn about.


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