T16992 fails with debug runtime
$ ghc-stage2 T16992.hs -O -fforce-recomp -debug
[1 of 1] Compiling Main ( T16992.hs, T16992.o )
Linking T16992 ...
$ ./T16992
T16992: internal error: ASSERTION FAILED: file rts/sm/Sanity.c, line 1018
(GHC version 8.11.0.20200530 for x86_64_unknown_linux)
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
zsh: abort (core dumped) ./T16992