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I've put mkSOName in HscTypes for now; I'm not sure what the best place
for it is.

This required various build system changes to get the build to go
through.

In the inplace shell wrappers, we set LD_LIBRARY_PATH to allow programs
to find their libraries. In the future, we might change the inplace tree
to be the same shape as an installed tree instead. However, this would
mean changing the way we do installation, as currently we use cabal's
installation methods to install the libraries, but that only works if
the libraries are under libraries/foo/dist-install/build/..., rather
than in inplace/lib/...

All the work was done by Dan Winograd-Cort.

The main thing is that arrow comamnds now have their own
data type HsCmd (defined in HsExpr).  Previously it was
punned with the HsExpr type, which was jolly confusing,
and made it hard to do anything arrow-specific.

To make this work, we now parameterise
  * MatchGroup
  * Match
  * GRHSs, GRHS
  * StmtLR and friends
over the "body", that is the kind of thing they
enclose.  This "body" parameter can be instantiated to
either LHsExpr or LHsCmd respectively.

Everything else is really a knock-on effect; there should
be no change (yet!) in behaviour.  But it should be a sounder
basis for fixing bugs.

See Trac #7287

Make sure that we check for type errors strictly in a Template Haskell splice, even if -fdefer-type-errors is on

We're going to run this code, so there's no point in deferring type
errors.  Worse, TcSplice uses unsafeCoerce (for vevy good reasons),
so splicing a type into a place where an expression is expected would
yield a seg-fault if we plough on regardless.

Fixes Trac #7276

This is just a bug that's been around since we introduced
polymorphic kinds.  The roots are in Type.cmpTypeX, but
there was a variant in TcRnDriver.checkBootTyCon, which
is where it came up.

Fixes Trac #7272

* Get rid of the lookupInInerts stage

* Re-introduce the flat-cache for flattening type-family equations
  See Note [Type family equations] in TcSMonad. My previous clever attempt
  with organising the work list proved too fragile.

  There's a (static) flag -fno-flat-cache to switch if off,
  so you can try with and without

* Improve the -ddump-cs-trace output

* The usual round of refactoring

The constraint solver sometimes goes to a lot of effort that turns
out to be Refl in the end, and avoiding zonking those proofs is a
useful optimisation. (Trac #5030)

This makes it easier to ensure that we get consistent consistency
checking, e.g. that
    -f1 -f2
will do the same checks as
    -f2 -f1

I think that some of the checks were bogus before, but hopefully
all are correct now.

It's still the case that
    -dynamic -static
will leave -fPIC enabled, but it's tricky to avoid that, and we already
have similar situations where for example
    -XRankNTypes -XNoRankNTypes
will leave ExplicitForAll enabled.

These variables all have uniformative names like "cobox" or "d".
Make them System Names tells the pretty printer to show their
uniques even without -dppr-debug.  That in turn makes the
less-voluminous debug traces *much* more informative.

We used to add the options when the way was enabled, but this caused
problems with the static/dynamic choice, as once the 'dynamic' options
had been added it wasn't easy to remove them. We therefore didn't allow
-static on the commandline if we'd already seen -static, which kludged
around the issue.

But apart from being unsatisfactory in the first place, this is a
problem if we want to allow -dynamic being on by default, as there
wouldn't be any way to turn it off.

So now we add C/CPP/linker flags required by the 'way's when flags
are requested, rather than during flag parsing.

This fixes Trac #7278

* Treat kind-equality constraints as *derived* equalities,
  with no evidence.  That is really what they are at the moment.

* Get rid of EvKindCast and friends.

* Postpone kind errors properly to the constraint solver
  (lots of small knock-on effects)

I moved SwapFlag to BasicTypes as well

The current fix is relatively dumb as far as where to add HpLim
checks: it will always perform a check unless we know that we're
returning from a closure or we are doing a non let-no-escape case
analysis.  The performance impact on the nofib suite looks like this:

            Min          +5.7%     -0.0%     -6.5%     -6.4%    -50.0%
            Max          +6.3%     +5.8%     +5.0%     +5.5%     +0.8%
 Geometric Mean          +6.2%     +0.1%     +0.5%     +0.5%     -0.8%

Overall, the executable bloat is the biggest problem, so we keep the old
omit-yields optimization on by default. Remember that if you need an
interruptibility guarantee, you need to recompile all of your libraries
with -fno-omit-yields.

A better fix would involve only inserting the yields necessary to break
loops; this is left as future work.
Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

This is a hopefully temporary measure until the new SRT design is
implemeented.