Cabal trouble

[Simon Peyton Jones]

Trying to build the repro case in Trac #14208, I get this

cabal install --with-ghc=/home/simonpj/5builds/ghc-8.4-branch/inplace/bin/ghc-stage2

Warning: cannot determine version of /home/simonpj/.cabal/bin/c2hs :

""

Resolving dependencies...

cabal: Could not resolve dependencies:

trying: exceptions-0.8.3 (dependency of streamly)

next goal: template-haskell (dependency of exceptions)

rejecting: template-haskell-2.13.0.0/installed-2.1... (conflict: exceptions =>

template-haskell>=2.2 && <2.13)

rejecting: template-haskell-2.12.0.0, template-haskell-2.11.1.0,

template-haskell-2.11.0.0, template-haskell-2.10.0.0,

template-haskell-2.9.0.0, template-haskell-2.8.0.0, template-haskell-2.7.0.0,

template-haskell-2.6.0.0, template-haskell-2.5.0.0, template-haskell-2.4.0.1,

template-haskell-2.4.0.0, template-haskell-2.3.0.1, template-haskell-2.3.0.0,

template-haskell-2.2.0.0 (constraint from non-upgradeable package requires

installed instance)

After searching the rest of the dependency tree exhaustively, these were the

goals I've had most trouble fulfilling: template-haskell, exceptions,

streamly, transformers, base
This is with my in-place build of GHC-8.4 (in-place but not modified in any way).  I've done a 'cabal upate'.
What am I doing wrong?
Thanks
Simon
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