Close #10709

Fixes #18767.

See updated Note [Use loose types in inert set] in
GHC.Tc.Solver.Monad.

Close #18753.

Some removed globals variables were still declared in the RTS.

They were removed in the following commits:

* 4fc6524a
* 0dc79856
* bbd3c399

There are still global variables but only 3 booleans instead of a single
DynFlags.

Necessary for recent Win32 bump.

Due to #17945.

Now `desugarLocalBind` (formerly `desugarLet`) reasons about

  * `FunBind`s that
    * Have no pattern matches (so which aren't functions)
    * Have a singleton match group with a single GRHS
    * (which may have guards)
  * and looks through trivial post-typechecking `AbsBinds` in doing so
    to pick up the introduced renamings.

And desugars to `PmLet` LYG-style guards. Since GRHSs are no longer
denoted simply by `NonEmpty PmGRHS`, but also need to carry a `[PmGrd]`
for the `PmLet`s from `LocalBind`s, I added `PmGRHSs` to capture that.

Since we call out to the desugarer more often, I found that there were
superfluous warnings emitted when desugaring e.g. case expressions.
Thus, I made sure that we deactivate any warnings in the LYG desugaring
steps by the new wrapper function `noCheckDs`.

There's a regression test in `T18626`. Fixes #18626.

Bump haddock submodule

!3220 ended up fixing #18501. This patch adds a regression
test for #18501 to ensure that it stays fixed.

_all_ of it, leaving nothing for, e.g., thread stacks.
Fix will only allocate 2/3rds and check whether remainder is at least large
enough for minimum amount of thread stacks.

Fixes #18699

Detect when the user forgets to enable the LinearTypes
extension and produce a better error message.

Steals the (a %m) syntax from TypeOperators, the workaround
is to write (a % m) instead.

Implements GHC Proposal #356

Updates the haddock submodule.

We were missing this case previously.

Close #18528.

Metric Decrease:
    T18223
    T5321Fun

This comment dates back to 3df40b7b
and does not seem relevant anymore.

The parser produces an AST where the (->)
is already associated correctly:

  1. (->) has the least possible precedence
  2. (->) is right-associative

Thus we don't need to handle it in mkHsOpTyRn.

As of 686e06c5,
GHC.Parser.PostProcess.mergeOps no longer exists.

[ci skip]

This was broken when we added multiplicity to the function type.

Reimplementation of integer-gmp's byteArrayToBigNat#

It's now named `GHC.Types.Unique.SDFM.UniqSDFM`.
The implementation is more clear about its stated goals and supported
operations.

  * Move everything from `GHC.HsToCore.PmCheck.*` to
    `GHC.HsToCore.Pmc.*` in analogy to `GHC.Tc`, rename exported
    `covCheck*` functions to `pmc*`
  * Rename `Pmc.Oracle` to `Pmc.Solver`
  * Split off the LYG desugaring and checking steps into their own
    modules (`Pmc.Desugar` and `Pmc.Check` respectively)
  * Split off a `Pmc.Utils` module with stuff shared by
    `Pmc.{,Desugar,Check,Solver}`
  * Move `Pmc.Types` to `Pmc.Solver.Types`, add a new `Pmc.Types` module
    with all the LYG types, which form the interfaces between
    `Pmc.{Desugar,Check,Solver,}`.

* Remove UnliftedFFITypes from conf. Some time ago, this extension
  was undocumented and we had to silence a warning.
  This is no longer needed.
* Use r'' in conf.py. This fixes a Sphinx warning:
  WARNING: Support for evaluating Python 2 syntax is deprecated and will be removed in Sphinx 4.0. Convert docs/users_guide/conf.py to Python 3 syntax.
* Mark GHCForeignImportPrim as documented
* Fix formatting in template_haskell.rst
* Remove 'recursive do' from the list of unsupported items in TH

* move backends into GHC.Num.Backend.*
* split backend selection into GHC.Num.Backend and
  GHC.Num.Backend.Selected to avoid duplication with the Check backend

Fixes #18439 .

The rhs of the pattern guard was consumed with multiplicity one, while
the pattern assumed it was Many. We use Many everywhere instead.

This is behaviour consistent with that of `case` expression. See #18738.

A RET_BIG closure has a large bitmap that describes it's payload and can
be printed with printLargeBitmap().

Additionally, the output for payload closures of small and big bitmaps is
changed: printObj() is used to print a bit more information about what's
on the stack.

The expected test output was plain wrong.
It has been fixed for a long time.
Thus we can close #17218.

The egregious performance hits are gone since !4050.
So we fix #18609.

They have been fixed by !3959, I believe.
Fixes #18371.

We now have a proper periodic clean-up script installed on the runners.