[GHC] #13889: GHC 8.0.2 panics when trying a simple snippet involving Parsec

[GHC]

#13889: GHC 8.0.2 panics when trying a simple snippet involving Parsec
-------------------------------------+-------------------------------------
           Reporter:  timmyjose      |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:  parsec,        |  Operating System:  MacOS X
  ghc8.0.2, macOS Sierra             |
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 I am working through "Create your own Scheme in 48 hours", and the
 following program:

 {{{
 $ cat SimpleParser.hs
 import Text.ParserCombinators.Parsec hiding (spaces)

 symbol :: Parser Char
 symbol = anyOf "!$%&|*+-/:<=?>@^_^~#"
 }}}

 causes GHC to crash and burn with a panic message.

 Please find the details as follows:

 ** PLATFORM and OS DETAILS **

 {{{
 $ sw_vers
 ProductName:    Mac OS X
 ProductVersion: 10.12.2
 BuildVersion:   16C67

 $ uname -a
 Darwin <elided> 16.3.0 Darwin Kernel Version 16.3.0: Thu Nov 17 20:23:58
 PST 2016; root:xnu-3789.31.2~1/RELEASE_X86_64 x86_64

 }}}

 ** GHC and Parsec version**

 {{{
 $ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 8.0.2

 $ ghc-pkg list | grep -i parsec
     attoparsec-0.13.1.0
     parsec-3.1.11
 }}}


 ** crash error message **
 {{{
 $ ghc -v3 SimpleParser.hs
 Glasgow Haskell Compiler, Version 8.0.2, stage 2 booted by GHC version
 7.10.3
 Using binary package database:
 /Library/Frameworks/GHC.framework/Versions/8.0.2-x86_64/usr/lib/ghc-8.0.2/package.conf.d/package.cache
 Using binary package database:
 /Users/<elided>/.ghc/x86_64-darwin-8.0.2/package.conf.d/package.cache
 loading package database
 /Library/Frameworks/GHC.framework/Versions/8.0.2-x86_64/usr/lib/ghc-8.0.2/package.conf.d
 loading package database
 /Users/<elided>/.ghc/x86_64-darwin-8.0.2/package.conf.d
 wired-in package ghc-prim mapped to ghc-prim-0.5.0.0
 wired-in package integer-gmp mapped to integer-gmp-1.0.0.1
 wired-in package base mapped to base-4.9.1.0
 wired-in package rts mapped to rts
 wired-in package template-haskell mapped to template-haskell-2.11.1.0
 wired-in package ghc mapped to ghc-8.0.2
 wired-in package dph-seq not found.
 wired-in package dph-par not found.
 Hsc static flags:
 loading package database
 /Library/Frameworks/GHC.framework/Versions/8.0.2-x86_64/usr/lib/ghc-8.0.2/package.conf.d
 loading package database
 /Users/z0ltan/.ghc/x86_64-darwin-8.0.2/package.conf.d
 wired-in package ghc-prim mapped to ghc-prim-0.5.0.0
 wired-in package integer-gmp mapped to integer-gmp-1.0.0.1
 wired-in package base mapped to base-4.9.1.0
 wired-in package rts mapped to rts-1.0
 wired-in package template-haskell mapped to template-haskell-2.11.1.0
 wired-in package ghc mapped to ghc-8.0.2
 wired-in package dph-seq not found.
 wired-in package dph-par not found.
 *** Chasing dependencies:
 Chasing modules from: *SimpleParser.hs
 !!! Chasing dependencies: finished in 0.62 milliseconds, allocated 0.337
 megabytes
 Stable obj: []
 Stable BCO: []
 Ready for upsweep
   [NONREC
       ModSummary {
          ms_hs_date = 2017-06-28 09:58:23 UTC
          ms_mod = Main,
          ms_textual_imps = [(Nothing, Prelude),
                             (Nothing, Text.ParserCombinators.Parsec)]
          ms_srcimps = []
       }]
 *** Deleting temp files:
 Deleting:
 compile: input file SimpleParser.hs
 *** Checking old interface for Main:
 [1 of 1] Compiling Main             ( SimpleParser.hs, SimpleParser.o )
 *** Parser [Main]:
 !!! Parser [Main]: finished in 0.20 milliseconds, allocated 0.134
 megabytes
 *** Renamer/typechecker [Main]:
 *** Deleting temp files:
 Deleting:
 *** Deleting temp dirs:
 Deleting:
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-apple-darwin):
         initTc: unsolved constraints
   WC {wc_insol = [W] anyOf_a1lw :: t_a1lv[tau:1] (CHoleCan: anyOf)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13889>
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