simonpj 2002/11/07 03:42:50 PST
Modified files:
ghc/compiler/deSugar DsUtils.lhs
Log:
------------------
Fix an obscure bug in implicit parameters,
interacting with lazy pattern matching
------------------
MERGE TO STABLE BRANCH
The problem was this:
data UniqueSupply = US Integer
newUnique :: (?uniqueSupply :: UniqueSupply) => Integer
newUnique = r
where US r = ?uniqueSupply
The lazy pattern match in the where clause killed GHC 5.04 because the
SourceType {?uniqueSupply::UniqueSupply} of the RHS of the 'where' didn't
look like a UniqueSupply.
The fix is simple: in DsUtils.mkSelectorBinds, use the pattern, not
the rhs, to get the type reqd. More efficient too.
Test is typecheck/should_compile/tc164.hs
Revision Changes Path
1.66 +19 -1 fptools/ghc/compiler/deSugar/DsUtils.lhs
_______________________________________________
Cvs-ghc mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/cvs-ghc
