[project @ 2004-10-20 13:34:04 by simonpj]
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Fix a bug in usage recording
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As a result of the new stuff on hi-boot-file consistency checking, I
accidentally caused Foo.hi to record a usage line for module Foo, and
this in turn caused rather nasty bad things to happen. In particular,
there were occasional crashes of form
ghc-6.3: panic! (the `impossible' happened, GHC version 6.3.
20041017):
forkM Constructor Var.TcTyVar{d r1B9}
At least I think that's why the crash happened.
Anyway, it was certainly a bug, and this commit fixes it. The main
payload of this fix is in Desugar.lhs; the rest is comments and
tidying.