[GHC] #16367: Panic when trying to openFile with -fdefer-type-errors (was: Panic when trying to openFile)

[GHC]

#16367: Panic when trying to openFile with -fdefer-type-errors
----------------------------------+--------------------------------------
        Reporter:  vilem          |                Owner:  (none)
            Type:  bug            |               Status:  new
        Priority:  normal         |            Milestone:
       Component:  GHCi           |              Version:  8.4.4
      Resolution:                 |             Keywords:
Operating System:  MacOS X        |         Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash  |            Test Case:
      Blocked By:                 |             Blocking:
 Related Tickets:                 |  Differential Rev(s):
       Wiki Page:                 |
----------------------------------+--------------------------------------
Changes (by vilem):

 * version:  8.4.3 => 8.4.4


Old description:

> {{{
> $ stack repl
>
> Note: No local targets specified, so a plain ghci will be started with no
> package hiding or package options.
>
>       If you want to use package hiding and options, then you can try one
> of the following:
>
>       * If you want to start a different project configuration than
> /Users/vl200/.stack/global-project/stack.yaml, then you can use stack
> init to create a new
>         stack.yaml for the packages in the current directory.
>
>       * If you want to use the project configuration at
> /Users/vl200/.stack/global-project/stack.yaml, then you can add to its
> 'packages' field.
>
> Configuring GHCi with the following packages:
> GHCi, version 8.4.3: http://www.haskell.org/ghc/  :? for help
> Loaded GHCi configuration from /Users/vl200/.ghci
> Loaded GHCi configuration from
> /private/var/folders/km/1g5b7h891674vhv9z1g4d9cw0000gn/T/haskell-stack-
> ghci/2a3bbd58/ghci-script
> Prelude> import System.IO
> Prelude System.IO> openFile ".g
> .granule    .gitignore  .ghc        .ghci       .gitconfig
> Prelude System.IO> openFile ".granule" Re
> Read           ReadMode       ReadS          ReadWriteMode  Real
> RealFloat      RealFrac       RelativeSeek
> Prelude System.IO> openFile ".granule" ReadMode
> ghc: panic! (the 'impossible' happened)
>   (GHC version 8.4.3 for x86_64-apple-darwin):
>         nameModule
>   system $dShow_a1QJ
>   Call stack:
>       CallStack (from HasCallStack):
>         callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in
> ghc:Outputable
>         pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name
>
> Please report this as a GHC bug:
> http://www.haskell.org/ghc/reportabug}}}

New description:

 {{{
 ~ ✔︎ ghci
 GHCi, version 8.4.4: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /Users/vl200/.ghci
 Prelude> :set -fdefer-type-errors
 Prelude> import System.IO
 Prelude System.IO> openFile ".granule" ReadWriteMode
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.4.4 for x86_64-apple-darwin):
         nameModule
   system $dShow_a1QU
   Call stack:
       CallStack (from HasCallStack):
         callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in
 ghc:Outputable
         pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name

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

 But works fine when I don't :set that option.

 {{{
 ~ ✔︎ ghci
 GHCi, version 8.4.4: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /Users/vl200/.ghci
 Prelude> import System.IO
 Prelude System.IO> openFile ".granule" ReadWriteMode
 {handle: .granule}
 Prelude System.IO>
 }}}

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16367#comment:2>
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