This proof had two `change`s added during porting, and these produce a massive timeout after the changes in leanprover/lean4#3807.

This PR replace the `change` with the appropriate `erw`, and is now fast before and after the change.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

.

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

This proof had two `change`s added during porting, and these produce a massive timeout after the changes in leanprover/lean4#3807.

This PR replace the `change` with the appropriate `erw`, and is now fast before and after the change.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

This proof had two `change`s added during porting, and these produce a massive timeout after the changes in leanprover/lean4#3807.

This PR replace the `change` with the appropriate `erw`, and is now fast before and after the change.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

This is the PR to `bump/v4.8.0`, bringing us up from
`nightly-2024-03-24` to `nightly-2024-04-07` (so almost two weeks).

Note that the release of v4.8.0-rc1 has been delayed because of
remaining issues:

This PR contains a number of `set_option maxHeartbeats ...` or `@[nolint
simpNF]` which are required by heartbeats errors.

These are due to changes to `IsDefEq` from
leanprover/lean4#3807.

So far, the ones I've looked in detail have revealed some problems where
we are probably abusing defeq a bit, so I would appreciate any available
eyes on these to see which ones ought to be fixed in Mathlib, and which
ones are problematic.

It's been a long road to keep `nightly-testing` alive, and some big
refactors have been landing on `master`, and I'm sure there are mistakes
in how I've merged things here, so please be gentle if I've messed
things up (and in particular feel free to revert changes that look like
mistakes, as long as you test them!). :-)

---------

Co-authored-by: Ruben Van de Velde <65514131+Ruben-VandeVelde@users.noreply.github.com>
Co-authored-by: María Inés de Frutos-Fernández <mariaines.dff@gmail.com>
Co-authored-by: María Inés de Frutos-Fernández <88536493+mariainesdff@users.noreply.github.com>
Co-authored-by: Parcly Taxel <reddeloostw@gmail.com>
Co-authored-by: Johan Commelin <johan@commelin.net>

This proof had two `change`s added during porting, and these produce a massive timeout after the changes in leanprover/lean4#3807.

This PR replace the `change` with the appropriate `erw`, and is now fast before and after the change.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

.

This is intended to fail at present: it just adds a test case containing
a minimization of a Mathlib slowdown from #3807.

Prior to #3807, the declaration `exists_algHom_adjoin_of_splits'''` at
the end of the file would take around 16,000 heartbeats. Now it takes
around 210,000 heartbeats.

---------

Co-authored-by: Leonardo de Moura <leomoura@amazon.com>

This proof had two `change`s added during porting, and these produce a massive timeout after the changes in leanprover/lean4#3807.

This PR replace the `change` with the appropriate `erw`, and is now fast before and after the change.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

These proofs will become slow after leanprover/lean4#3807, but with these changes there is no regression. 🤷‍♀️

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>