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

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