[GHC] #15321: Typed holes in Template Haskell splices produce bewildering error messages

[GHC]

#15321: Typed holes in Template Haskell splices produce bewildering error messages
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Template Haskell  |              Version:  8.4.3
      Resolution:                    |             Keywords:  TypedHoles
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by mgsloan):

 I'm trying to get more familiar with working on GHC / TH, so took a look
 at the trac issues.  This one seemed interesting to resolve, so I took a
 look.  Just writing a note here so that y'all know there is work in
 progress here.  I think I've figured it out!

 Indeed, when searching for valid hole fits, it is considering names that
 come from the current module, even when in a TH splice.  My plan is to
 check `tcl_th_ctxt` to see if we're in a splice, and in that case omit
 `lcl` (module locals) from the computation of `locals` in
 `findValidHoleFits`. `lclBinds` will still be used, since locals within
 the splice certainly should be checked for fitting.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15321#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler