This has already been patched upstream, but not yet released. See: https://github.com/haskell/vector/commit/c3616f425bf1caabf21872697610e75e61308b63

Cabal-3.2.1.0 and Cabal-syntax-3.8.1.0 need updating to account
for the bugfix in GHC MR !11107 which means that an import of Rep(..)
no longer brings the class methods of Generic into scope.

This patch enables the TypeAbstractions extension in singletons-base
on GHC >= 9.8, as the extension is now required for invisible binders
in type declarations, which are used pervasively throughout the library.

The `__GLASGOW_HASKELL__` macro was missing its underscores.

GHC MR !11112 makes it so that one needs to enable the (new)
TypeAbstractions extension in order to use type applications in
constructor patterns. The old behaviour (ScopedTypeVariables + TypeApplications)
is still supported, but it emits a warning, which causes sbv to fail
to build due to -Werror.

In addition, the changes in GHC MR !11112 mean that the use of invisible
binders in type declarations requires the TypeAbstractions extension
to be enabled.

`isUnsafeEqualityProof` was removed in favor of `isUnsafeEqualityCase` in
ghc/ghc@59202c80.

Fixes #40.

For now, we must use `__GLASGOW_HASKELL__ >= 907` instead of
`MIN_VERSION_template_haskell(2,21,0)`, as the `template-haskell` version has
not yet been changed to `template-haskell-2.21.0.0` on GHC's `master` branch
(see ghc/ghc!10936).