#6002: GHC 7.4+ thinks class instance is incoherent, 7.0.4 disagrees
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Reporter: heisenbug | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: GHC rejects valid program
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonpj@…):
commit 6bf815982df88468035593a07b0be593d1326af2
{{{
Author: Simon Peyton Jones <[email protected]>
Date: Fri Apr 13 12:54:44 2012 +0100
Allow overlaps when -XIncoherentInstances is in force
This change allows a top-level instance to be used even if there is
a (potentially) overlapping local given. Which isn't fab, but it is
what IncoherentInstances is *for*.
This fixes the bug part of Trac #6002.
compiler/typecheck/TcInteract.lhs | 18 ++++++++++--------
1 files changed, 10 insertions(+), 8 deletions(-)
}}}
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6002#comment:4>
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