#3102: The impossible happened with implicit parameters
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Reporter: Ashley Yakeley | Owner: igloo
Type: merge | Status: new
Priority: normal | Milestone: 6.12.1
Component: Compiler (Type checker) | Version: 6.10.1
Resolution: | Keywords:
Difficulty: Unknown | Os: Linux
Testcase: tyepcheck/should_fail/T3102 | Architecture: Unknown/Multiple
Failure: None/Unknown |
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Changes (by simonpj):
* testcase: => tyepcheck/should_fail/T3102
* status: reopened => new
* type: bug => merge
* owner: chak => igloo
Comment:
You're right. There was another bug lurking.
{{{
Mon Nov 30 09:44:41 PST 2009 simo...@microsoft.com
* Fix Trac #3102: pre-matching polytypes
When *pre-matching* two types
forall a. C1 => t1 ~ forall a. C2 => t2
we were matching t1~t2, but totally ignoring C1,C2
That's utterly wrong when pre-matching
(?p::Int) => String ~ a
because we emerge with a:=String!
All this is part of the impredicative story, which is about
to go away, but still.
Worth merging this to 6.12
M ./compiler/typecheck/TcUnify.lhs -2 +3
}}}
Merge if possible to 6.12.
Thanks for being persistent.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3102#comment:6>
GHC <http://www.haskell.org/ghc/>
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