Matthew Craven authored 1 year ago and Cheng Shao committed 6 months ago

Fixes #23117. Fixes #23281. Fixes #23490.

This required:
 * Updating the bit-rotted compiler/Setup.hs and its setup-depends
 * Listing a few recently-added libraries and utilities
   in cabal.project-reinstall
 * Setting allow-boot-library-installs to 'True' since Cabal
   now considers the 'ghc' package itself a boot library for
   the purposes of this flag

Additionally, the allow-newer block in cabal.project-reinstall
was removed.  This block was probably added because when the
libraries/Cabal submodule is too new relative to the cabal-install
executable, solving the setup-depends for any package with a custom
setup requires building an old Cabal (from Hackage) against the
in-tree version of base, and this can fail un-necessarily due to
tight version bounds on base.  However, the blind allow-newer can
also cause the solver to go berserk and choose a stupid build plan
that has no business succeeding, and the failures when this happens
are dreadfully confusing. (See #23281 and #24363.)

Why does setup-depends solving insist on an old version of Cabal? See:
  https://github.com/haskell/cabal/blob/0a0b33983b0f022b9697f7df3a69358ee9061a89/cabal-install/src/Distribution/Client/ProjectPlanning.hs#L1393-L1410

The right solution here is probably to use the in-tree cabal-install
from libraries/Cabal/cabal-install with the build-cabal target rather
than whatever the environment happens to provide.  But this is left
for future work.