GHC HEAD fails to build with `-fspecialize-aggressively -fexpose-all-unfoldings`
Running hadrian/build -j6 --flavour=default+no_profiled_libs "stage1.*.ghc.hs.opts += -fspecialize-aggressively -fexpose-all-unfoldings" -o_spec_trans
I get this panic:
ghc: panic! (the 'impossible' happened)
GHC version 9.7.20230104:
lookupIdSubst
v_sa3N
InScope {s_aa6X eta_aa6Z debugTerminalKeys $trModule loc_s8n5
loc_s8n6 loc_s8n7 loc_s8n8 loc_s8n9 loc_s8na loc_s8nb $dIP_s8nc
...
...
...
$dMonad_sa70}
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/GHC/Utils/Panic.hs:189:37 in ghc:GHC.Utils.Panic
pprPanic, called at compiler/GHC/Core/Subst.hs:197:17 in ghc:GHC.Core.Subst
CallStack (from HasCallStack):
panic, called at compiler/GHC/Utils/Error.hs:454:29 in ghc:GHC.Utils.Error