#4841: TypeSynonymInstances allow some flexible instances
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Reporter: benmachine | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version: 7.0.1
Resolution: fixed | Keywords:
Testcase: | Blockedby:
Difficulty: | Os: Unknown/Multiple
Blocking: | Architecture: Unknown/Multiple
Failure: GHC accepts invalid program |
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Changes (by simonpj):
* status: new => closed
* resolution: => fixed
Comment:
Fixed by
{{{
Tue Dec 14 09:47:55 PST 2010 [email protected]
* Fix Trac #4841: behave right with TypeSynonymInstances and
NoFlexibleInstances
When we have TypeSynonymInstances without FlexibleInstances we should
still
insist on a H98-style instance head, after looking through the synonym.
This patch also make FlexibleInstances imply TypeSynonymInstances.
Anything
else is a bit awkward, and not very useful.
M ./compiler/main/DynFlags.hs +1
M ./compiler/typecheck/TcType.lhs +3
M ./docs/users_guide/flags.xml -2 +3
}}}
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4841#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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