GHC panic with duplicate exports due to record pattern synonym

Summary

GHC panics when a duplicate export is from a record pattern synonym and another module attempts to import it.

Steps to reproduce

With these two files:

bad1.hs:

{-# LANGUAGE PatternSynonyms #-}

module Bad1 (T(TSyn, getTSyn), getTSyn) where

data T = T Int
pattern TSyn :: Int -> T
pattern TSyn {getTSyn} <- T getTSyn where
  TSyn i = T i

bad2.hs:

module Bad2 where

import Bad1 (getTSyn)

Run ghc ./bad1.hs ./bad2.hs should result in this output:

bad1.hs:3:32: warning: [-Wduplicate-exports]
    ‘getTSyn’ is exported by ‘getTSyn’ and ‘T(TSyn, getTSyn)’
  |
3 | module Bad1 (T(TSyn, getTSyn), getTSyn) where
  |                                ^^^^^^^
[2 of 2] Compiling Bad2             ( bad2.hs, bad2.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 8.8.4 for x86_64-unknown-linux):
        filterImports/combine
  (getTSyn, getTSyn, Nothing)
  (getTSyn, T{T, TSyn, getTSyn;}, Nothing)
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1159:37 in ghc:Outputable
        pprPanic, called at compiler/rename/RnNames.hs:899:23 in ghc:RnNames

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

Expected behavior

This should be accepted, since the exporting module compiled

Environment

• GHC version used: 8.8.4

Optional:

• Operating System: Linux (NixOS)
• System Architecture: AMD64