Martin Norbäck writes:

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The GHC manual needs to specify what happens when you use -odir and hierarchical modules with --make.

It may be of interest to note that hmake currently uses solution 2 below.

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Solution 2: files put in -odir are put in directories (files will end up in Program/output/Bar/Module.o and Program/output/Foo/Module.o) This is also a slight change in semantics, since files are put in directories. May affect Makefiles that does "ar output/*.o" or similar.

And this is also what the current CVS version of GHC does. Note that you need to create the directories if they don't exist (GHC won't do it for you). Please also see http://www.haskell.org/pipermail/glasgow-haskell-users/2002-December/004569...., which contains a specification of GHC's current search strategy. Cheers, Simon