[GHC] #15007: Don't keep shadowed variables in ghci, both renamer and type checker

[GHC]

#15007: Don't keep shadowed variables in ghci, both renamer and type checker
-------------------------------------+-------------------------------------
        Reporter:  sighingnow        |                Owner:  sighingnow
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  GHCi              |              Version:  8.5
      Resolution:                    |             Keywords:  TypedHoles
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11547 #14052     |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * keywords:   => TypedHoles


Old description:

> In ticket:14052, we reverted Phab:D2447, then ticket:11547 exists in HEAD
> again. In ticket:14052#comment:25 and ticket:14052#comment:10, we decide
> that shadowed variables shouldn't be keep at all. This ticket is created
> to track the idea.
>
> The same error of ticket:11547 was also reported in
> ticket:14996#comment:2,
>
> > {{{#!hs
> > $ inplace/bin/ghc-stage2 --interactive
> > GHCi, version 8.5.20180403: http://www.haskell.org/ghc/  :? for help
> > Prelude> 1
> > 1
> > Prelude> 1
> > 1
> > Prelude> _
> >
> > <interactive>:1:1: error:
> >     GHC internal error: ‘Ghci1.it’ is not in scope during type >
> checking, but it passed the renamer
> >    tcl_env of environment: []
> >}}}
> >
> > (giving "1" twice is needed to reproduce the error)
>
> NB: input "1" twice to create shadowed context is necessary to reproduce
> this bug.

New description:

 In ticket:14052, we reverted Phab:D2447, then ticket:11547 exists in HEAD
 again. In ticket:14052#comment:25 and ticket:14052#comment:10, we decide
 that shadowed variables shouldn't be keep at all. This ticket is created
 to track the idea.

 The same error of ticket:11547 was also reported in
 ticket:14996#comment:2,

 > {{{
 > $ inplace/bin/ghc-stage2 --interactive
 > GHCi, version 8.5.20180403: http://www.haskell.org/ghc/  :? for help
 > Prelude> 1
 > 1
 > Prelude> 1
 > 1
 > Prelude> _
 >
 > <interactive>:1:1: error:
 >     GHC internal error: ‘Ghci1.it’ is not in scope during type >
 checking, but it passed the renamer
 >    tcl_env of environment: []
 >}}}
 >
 > (giving "1" twice is needed to reproduce the error)

 NB: input "1" twice to create shadowed context is necessary to reproduce
 this bug.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15007#comment:2>
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