Why can't we re-install the template-haskell package?

Dear friends, as I'm working on making lib:ghc re-installable [1][2]. Ideally I'd prefer we only had to freeze rts + ghc-prim and maybe base (which would implicate the integer library). However, we apparently can't re-install Template Haskell I'm told. Not just not upgrade it, but not even re-install it (same version). I've attached some rough dependency graph (which I hope is correct for ghc 8.8). Fixing template-haskell implies ghc-boot-th, pretty, deepseq and array. Can someone shed some light onto the details here? What are the fundamental issues we can't reinstall template-haskell? Cheers, Moritz -- [1]: https://gitlab.haskell.org/ghc/ghc/merge_requests/490 [2]: https://gitlab.haskell.org/ghc/ghc/merge_requests/506