Mon Sep 25 05:13:51 PDT 2006 [EMAIL PROTECTED]
* Fix newtype deriving properly (un-doing Audreys patch)
The newtype-deriving mechanism generates a HsSyn case expression looking
like this
case (d `cast` co) of { ... }
That is, the case expression scrutinises a dictionary. This is
otherwise never seen in HsSyn, and it made the desugarer
(Check.get_unused_cons) crash in tcTyConAppTyCon.
It would really be better to generate Core in TcInstDecls (the newtype
deriving part) but I'm not going to do that today. Instead, I made
Check.get_unused_cons a bit more robust.
Audrey tried to fix this over the weekend, but her fix was, alas, utterly
bogus, which caused mysterious failures later. I completely undid this
change.
Anyway it should work now!
M ./compiler/deSugar/Check.lhs -6 +6
M ./compiler/typecheck/TcClassDcl.lhs +2
M ./compiler/typecheck/TcInstDcls.lhs +3
M ./compiler/typecheck/TcType.lhs -11 +7
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