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Simon Peyton Jones authored
------------------------------------- Improve the "unused binding" warnings ------------------------------------- We've had a succession of hacks for reporting warnings for unused bindings. Consider module M( f ) where f x = x g x = g x + h x h x = x Here, g mentions itself and h, but is not itself mentioned. So really both g and h are dead code. We've been getting this wrong for ages, and every hack so far has failed on some simple programs. This commit does a much better job. The renamer applied to a bunch of bindings returns a NameSet.DefUses, which is a dependency-ordered lists of def/use pairs. It's documented in NameSet. Given this, we can work out precisely what is not used, in a nice tidy way. It's less convenient in the case of type and class declarations, because the strongly-connected-component analysis can span module boundaries. So things are pretty much as they were for these. As usual, there was a lot of chuffing around tidying things up. I havn't tested it at all thoroughly yet. Various unrelated import-decl-pruning has been done too.
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