[GHC] #12921: initTc: unsolved constraints

[GHC]

#12921: initTc: unsolved constraints
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        Reporter:  jlp               |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13106            |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * cc: simonpj (added)


Comment:

 Simon's commit 1ef274298978369e2e07b5c43e635a5ca529a0af:

 {{{
 From 1ef274298978369e2e07b5c43e635a5ca529a0af Mon Sep 17 00:00:00 2001
 From: Simon Peyton Jones <simonpj at microsoft.com>
 Date: Thu, 13 Oct 2016 12:24:53 +0100
 Subject: [PATCH] Further improve error handling in TcRn monad

 This patch builds on the one for Trac #12124, by dealing properly
 with out-of-scope "hole" errors.

 This fixes Trac #12529. The hard error coming from visible type
 application
 is still there, but the out-of-scope error is no longer suppressed.

 (Arguably the VTA message should be suppressed somehow, but that's a
 battle for another day.)
 }}}

 caused this (and #13106).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12921#comment:3>
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