Following the model of the other printf symbols. See Note [Symbols for
MinGW's printf].

Closes #18838.

These were incorrectly removed in a recent cleanup commit.

This should have been done when the toolchain was bumped.

This widens LocalLabel to 2^16, avoiding the crash observed in #14334.

Closes #14334.

As well a ctuples and sums.

Makes it possible for GHC to optimize away intermediate Generic representation
for more types.

Metric Increase:
    T12227

This otherwise fails on newer Clangs, which warn
more aggressively on undeclared symbols.

-fPIE and -fno-PIE flags were (un)setting Opt_PIC instead of Opt_PIE.

Original commit: 3625728a

No longer neccessary - TypeRep is now indexed, there is no ambiguity.

Also fix a comment in Evidence.hs, IsLabel no longer takes a Proxy#.

There are two signficant changes here:

* Ticket #18815 showed that we were missing some opportunities for
  preInlineUnconditionally.  The one-line fix is in the code for
  GHC.Core.Opt.Simplify.Utils.preInlineUnconditionally, which now
  switches off only for INLINE pragmas.  I expanded
  Note [Stable unfoldings and preInlineUnconditionally] to explain.

* When doing this I discovered a way in which preInlineUnconditionally
  was occasionally /too/ eager.  It's all explained in
  Note [Occurrences in stable unfoldings] in GHC.Core.Opt.OccurAnal,
  and the one-line change adding markAllMany to occAnalUnfolding.

I also got confused about what NoUserInline meant, so I've renamed
it to NoUserInlinePrag, and changed its pretty-printing slightly.
That led to soem error messate wibbling, and touches quite a few
files, but there is no change in functionality.

I did a nofib run.  As expected, no significant changes.

        Program           Size    Allocs
----------------------------------------
         sphere          -0.0%     -0.4%
----------------------------------------
            Min          -0.0%     -0.4%
            Max          -0.0%     +0.0%
 Geometric Mean          -0.0%     -0.0%

I'm allowing a max-residency increase for T10370, which seems
very irreproducible. (See comments on !4241.)  There is always
sampling error for max-residency measurements; and in any case
the change shows up on some platforms but not others.

Metric Increase:
    T10370

```----------------------
Metric Decrease:
   T12425
Metric Increase:
   T17516
```

----------------------

This fixes a regression introduced in 2b89ca5b
See the new T18151x test case.

The issue described in that section was fixed by
2b89ca5b

Previously, the use of kind-level literals, promoted tuples,
and promoted lists required enabling both `DataKinds` and
`PolyKinds`. This made sense back in a `TypeInType` world, but not so
much now that `TypeInType`'s role has been superseded. Nowadays,
`PolyKinds` only controls kind polymorphism, so let's make `DataKinds`
the thing that controls the other aspects of `TypeInType`, which include
literals, promoted tuples and promoted lists.

There are some other things that overzealously required `PolyKinds`,
which this patch fixes as well:

* Previously, using constraints in kinds (e.g., `data T :: () -> Type`)
  required `PolyKinds`, despite the fact that this is orthogonal to kind
  polymorphism. This now requires `DataKinds` instead.
* Previously, using kind annotations in kinds
  (e.g., `data T :: (Type :: Type) -> Type`) required both `KindSignatures`
  and `PolyKinds`. This doesn't make much sense, so it only requires
  `KindSignatures` now.

Fixes #18831.

Fixes #18267.

As noted in #18726, this regularly breaks. Let's test it.

Note that we don't actually perform a build of GHC itself; we merely
test that the Hadrian executable builds and works (by invoking `hadrian
--version`).

This commit removes the separate kind 'Nat' and enables promotion
of type 'Natural' for using as type literal.
It partially solves #10776

Now the following code will be successfully typechecked:
    data C = MkC Natural
    type CC = MkC 1

Before this change we had to create the separate type for promotion
    data C = MkC Natural
    data CP = MkCP Nat
    type CC = MkCP 1

But CP is uninhabited in terms.

For backward compatibility type synonym `Nat` has been made:
    type Nat = Natural

The user's documentation and tests have been updated.
The haddock submodule also have been updated.

The HomeUnitId is only used by the Cmm parser and this one has access to
the DynFlags, so it can grab the UnitId of the HomeUnit from them.

Bump haddock submodule

Metric Decrease:
    Naperian
    T10421
    T10421a
    T10547
    T12150
    T12234
    T12425
    T13035
    T18140
    T18304
    T5837
    T6048
    T13253-spj
    T18282
    T18223
    T3064
    T9961
Metric Increase
    T13701

HFSKJH

Make demand analysis usable without having to provide DynFlags.

Before this patch, referring to a data constructor in a term-level
context led to a scoping error:

    ghci> id Int
    <interactive>:1:4: error: Data constructor not in scope: Int

After this patch, the renamer falls back to the type namespace
and successfully finds the Int. It is then rejected in the type
checker with a more useful error message:

    <interactive>:1:4: error:
    • Illegal term-level use of the type constructor ‘Int’
        imported from ‘Prelude’ (and originally defined in ‘GHC.Types’)
    • In the first argument of ‘id’, namely ‘Int’
      In the expression: id Int

We also do this for type variables.

Instead of recreating the HomeUnit from the DynFlags every time we need
it, we store it in the HscEnv.

!3798 added documentation and semantics for the flags,
but not parsing.

Firstly this improves code clarity.

But it also has performance benefits as we no longer
go through the name of the TyCon to get at it's unique.

In order to make this work the recursion check for TyCon
has been moved into it's own module in order to avoid import
cycles.

This should fix #18774.

This fixes a long-standing bug in the desugaring of record
updates for data families, when the latter involves a GADT. It's
all explained in Note [Update for GADTs] in GHC.HsToCore.Expr.

Building the correct cast is surprisingly tricky, as that Note
explains.

Fixes #18809.  The test case (in indexed-types/should_compile/T18809)
contains several examples that exercise the dark corners.