[GHC] #1: Implicit parameters cause strange behavi

[GHC]

#1: Implicit parameters cause strange behavi
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       Reporter:  nobody        |      Owner:  nobody
           Type:  bug           |     Status:  closed
       Priority:  normal        |  Milestone:
      Component:  Compiler      |    Version:  5.0
     Resolution:  Fixed         |   Keywords:
Type of failure:  None/Unknown  |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"91822e4eee295a42f69489c7e9e878b296e897bc/ghc"
 91822e4e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="91822e4eee295a42f69489c7e9e878b296e897bc"
 Add "quantified constraint" context in error message, fix #15231.

 This patch adds "quantified constraint" context in error message when
 UndecidableInstances checking fails for quantified constraints.
 See Trac #15231:comment#1.

 This patch also pretty-prints the instance head for better error messages.

 Test Plan: make test TEST="T15231"

 Reviewers: bgamari, simonpj

 Reviewed By: simonpj

 Subscribers: simonpj, rwbarton, thomie, carter

 GHC Trac Issues: #15231

 Differential Revision: https://phabricator.haskell.org/D4819
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1#comment:6>
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