[GHC] #13473: Variables in patterns made with QuasiQuotes sometimes don't get bound

[GHC]

#13473: Variables in patterns made with QuasiQuotes sometimes don't get bound
-------------------------------------+-------------------------------------
        Reporter:  harpocrates       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Template Haskell  |              Version:  8.0.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * cc: facundominguez (added)
 * component:  Compiler => Template Haskell


Comment:

 This regression appeared between GHC 8.0.1 and 8.0.2. I tracked it down to
 commit 8d63419478074728eb03082787ea51d498b3e62e:

 {{{
 From 8d63419478074728eb03082787ea51d498b3e62e Mon Sep 17 00:00:00 2001
 From: =?utf8?q?Facundo=20Dom=C3=ADnguez?= <facundo.dominguez at tweag.io>
 Date: Wed, 6 Jul 2016 06:48:27 -0300
 Subject: [PATCH] Have addModFinalizer expose the local type environment.

 Summary:
 This annotates the splice point with 'HsSpliced ref e' where 'e' is the
 result of the splice. 'ref' is a reference that the typechecker will fill
 with
 the local type environment.

 The finalizer then reads the ref and uses the local type environment,
 which
 causes 'reify' to find local variables when run in the finalizer.
 }}}

 Thoughts, Facundo?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13473#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler