GHC 8.6.1 can't be bootstrapped with GHC 8.2.1

60e4bb4d (#9136 (closed)) triggers a bug in GHC 8.2.1 which causes the build to fail with,

ghc: panic! (the 'impossible' happened)
  (GHC version 8.2.1 for x86_64-unknown-linux):
	runtimeRepPrimRep
  typePrimRep (r_aqbE :: TYPE rep_aqbD)
  rep_aqbD
  Call stack:
      CallStack (from HasCallStack):
        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable
        callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable
        pprPanic, called at compiler/simplStg/RepType.hs:360:5 in ghc:RepType

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

This is a manifestation of #14393 (closed), which is fixed in 8.2.2 and later.

We should probably add a configure check warning about this brokenness when the user tries to bootstrap with GHC 8.2.1.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture