Template Haskell record splices are not renamer-resolved correctly.

While working on ticket #8761 (closed), I noticed that splicing in record selectors with Template Haskell seems to cause renamer issues in GHC HEAD.

Consider the following TH splice:

{- Test splicing in a data type with records -}
[d|
 data D a = MkD { unD :: a }

 someD = MkD "Hello"
 getD  = unD someD      -- unD should resolve to the record selector above!
 |]

getD' = unD someD       -- dito here outside of the splice!

While GHC 7.10.3 accepts this splice and renames it correctly, GHC HEAD fails with the following error message (with -ddump-splices enabled):

[1 of 1] Compiling Error            ( Error.hs, Error.o )
Error.hs:(6,1)-(11,3): Splicing declarations
    [d| someD_apF = MkD_apD "Hello"
        getD_apG = unD someD_apF
        
        data D_apC a_apH = MkD_apD {unD :: a_apH} |]
  ======>
    data D_a4SA a_a4SD = MkD_a4SB {unD_a4SC :: a_a4SD}
    someD_a4Sy = MkD_a4SB "Hello"
    getD_a4Sz = unD_a4SC someD_a4Sy

Error.hs:6:1: error:
    The exact Name ‘unD_a4SC’ is not in scope
      Probable cause: you used a unique Template Haskell name (NameU), 
      perhaps via newName, but did not bind it
      If that's it, then -ddump-splices might be useful

I'm not sure as to what introduced this bug, but investigating it I found that the notes

• NOTE [Binders in Template Haskell] in Convert.hs, and
• NOTE [Looking up Exact RdrNames] in RnEnv.hs

are not respected by function newRecordSelector in rename/RnNames.hs. I've fixed this function accordingly in D1940 for #8761 (closed), but since that patch is not going to be part of 8.0.1, Richard suggested to fix it separately in this ticket.

I'm submitting a patch in due course.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Template Haskell
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