Teo Camarasu authored Apr 03, 2024 and Marge Bot committed Apr 16, 2024

Promoting template-haskell from a stage0 to a stage1 package means that
we can much more easily refactor template-haskell.

We implement this by duplicating the in-tree `template-haskell`.
A new `template-haskell-next` library is autogenerated to mirror `template-haskell`
`stage1:ghc` to depend on the new interface of the library including the
`Binary` instances without adding an explicit dependency on `template-haskell`.

This is controlled by the `bootstrap-th` cabal flag

When building `template-haskell` modules as part of this vendoring we do
not have access to quote syntax, so we cannot use variable quote
notation (`'Just`). So we either replace these with hand-written `Name`s
or hide the code behind CPP.

We can remove the `th_hack` from hadrian, which was required when
building stage0 packages using the in-tree `template-haskell` library.

For more details see Note [Bootstrapping Template Haskell].

Resolves #23536



Co-Authored-By: Sebastian Graf <sgraf1337@gm...>