Tue Jul 21 22:09:33 PDT 2009 simo...@microsoft.com
* Take account of GADTs when reporting patterm-match overlap
Ignore-this: 7dcbdcb91021e83e6e6208a2e68c50c9
When matching against a GADT, some of the constructors may be impossible.
For example
data T a where
T1 :: T Int
T2 :: T Bool
T3 :: T a
f :: T Int -> Int
f T1 = 3
f T3 = 4
Here, does not have any missing cases, despite omittting T2, because
T2 :: T Bool.
This patch teaches the overlap checker about GADTs, which happily
turned out to be rather easy even though the overlap checker needs
a serious rewrite.
M ./compiler/deSugar/Check.lhs -6 +9
M ./compiler/typecheck/TcTyClsDecls.lhs -1 +8
View patch online:
http://darcs.haskell.org/ghc/_darcs/patches/20090722050933-1287e-d07a71da1e5456f4c1ada3fc15adf183e532fff1.gz
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