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As reported in Trac #10891, Template Haskell's `reify` was not generating Decls
for associated types. This patch fixes that.

Note that even though `reifyTyCon` function used in this patch returns some
type instances, I'm ignoring that.

Here's an example of how associated types are encoded with this patch:

(Simplified representation)

    class C a where
      type F a :: *

    -->

    OpenTypeFamilyD "F" ["a"]

With default type instances:

    class C a where
      type F a :: *
      type F a = a

    -->

    OpenTypeFamilyD "F" ["a"]
    TySynInstD "F" (TySynEqn [VarT "a"] "a")

Reviewed By: goldfire

Differential Revision: https://phabricator.haskell.org/D1254

GHC Trac Issues: #10891

Previously it was only available from GHC.Conc, but it makes sense for it to be
available from a more official place where people might find it.

While I was here, I improved the docs a little.

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D1272

This should (1) fix the ./validate build, which I accidentally broke in D1168,
and (2) update the Cabal submodule so that it recognizes `DeriveLift` as a GHC
extension.

Reviewed By: adamse, austin

Differential Revision: https://phabricator.haskell.org/D1269

GHC Trac Issues: #1830

This adds a constant-folding rule for `Integer`'s implementation of `bit` and
fixes the `T8832` testcase. Fixes #8832.

Reviewed By: simonpj, austin

Differential Revision: https://phabricator.haskell.org/D1255

GHC Trac Issues: #8832

Summary:
This allows the code generator to give hints to later code generation
steps about which branch is most likely to be taken.  Right now it
is only taken into account in one place: a special case in
CmmContFlowOpt that swapped branches over to maximise the chance of
fallthrough, which is now disabled when there is a likelihood setting.

Test Plan: validate

Reviewers: austin, simonpj, bgamari, ezyang, tibbe

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1273

Previously CallStacks would be built using String, which would pull in
GHC.Base while compiling GHC.Err. Use [Char] instead.

Previously the types needlessly used (), which is defined ghc-prim,
leading to unfortunate import cycles. See #10867 for details.

Updates stm submodule.

A few tests had the same name which is a big no-no, so I reorganized them a
little. The naming is somewhat haphazard, though...
Signed-off-by: Austin Seipp <austin@well-typed.com>

Clang's CPP implementation seems to barf otherwise

Summary:
This implements -XDeriveLift, which allows for automatic derivation
of the Lift class from template-haskell. The implementation is based
off of Ian Lynagh's th-lift library
(http://hackage.haskell.org/package/th-lift).

Test Plan: ./validate

Reviewers: hvr, simonpj, bgamari, goldfire, austin

Reviewed By: goldfire, austin

Subscribers: osa1, thomie

Differential Revision: https://phabricator.haskell.org/D1168

GHC Trac Issues: #1830

The names of auxiliary bindings end up in the interface file, and since uniques
are nondeterministic, we end up with nondeterministic interface files.

This uses the package and module name in the generated name, so I believe it
should avoid problems from #7947 and be deterministic as well.

The generated names look like this now:

  `$cLrlbmVwI3gpI8G2E6Hg3mO`

and with `-ppr-debug`:

  `$c$aeson_70dylHtv1FFGeai1IoxcQr$Data.Aeson.Types.Internal$String`.

Reviewed By: simonmar, austin, ezyang

Differential Revision: https://phabricator.haskell.org/D1133

GHC Trac Issues: #4012

The default top-level exception handler now uses the `Show` instance for
`ErrorCall` when printing exceptions, so it will actually print the out-of-band
data (e.g. `CallStack`s) in compiled binaries, instead of just printing the
error message.

This also updates the hpc submodule to fix the test output.

Reviewed By: austin, thomie

Differential Revision: https://phabricator.haskell.org/D1217

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

It's unlikely that these lists would have become very large but
nevertheless this is an easy and worthwhile change.

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D1265

It's not used anywhere.

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D1266

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

This patch drops the file level distinction between hs-boot and hsig;
we figure out which one we are compiling based on whether or not there
is a corresponding hs file lying around.

To make the "import A" syntax continue to work for bare hs-boot
files, we also introduce hs-boot merging, which takes an A.hi-boot
and converts it to an A.hi when there is no A.hs file in scope.
This will be generalized in Backpack to merge multiple A.hi files together;
which means we can jettison the "load multiple interface files" functionality.

This works automatically for --make, but for one-shot compilation
we need a new mode: ghc --merge-requirements A will generate an A.hi/A.o
from a local A.hi-boot file; Backpack will extend this mechanism further.

Has Haddock submodule update to deal with change in msHsFilePath behavior.

    - This commit drops support for the hsig extension. Can
      we support it?  It's annoying because the finder code is
      written with the assumption that where there's an hs-boot
      file, there's always an hs file too.  To support hsig, you'd
      have to probe two locations.  Easier to just not support it.

    - #10333 affects us, modifying an hs-boot still doesn't trigger
      recomp.

    - See compiler/main/Finder.hs: this diff is very skeevy, but
      it seems to work.

    - This code cunningly doesn't drop hs-boot files from the
      "drop hs-boot files" module graph, if they don't have a
      corresponding hs file.  I have no idea if this actually is useful.
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: simonpj, austin, bgamari, spinda

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1098

This reverts commit 0c6c015d.

This reverts commit 214596de.

Thanks for the suggestion, Austin. Just missed that while making
a bunch of similar changes.

Now we use Array to store branches. This makes sense because we often
have to do random access (once inference is done). This also vastly
simplifies the awkward BranchList type.

This fixes #10837 and updates submodule utils/haddock.

This fixes #10896. In the indexed-types/should_fail/BadSock test,
there is a bad type definition. This gets type-checked, an error
gets reported, but then **GHC keeps going**. Later, when
running the simplifier to do an ambiguity check, the bad type
environment causes GHC to fall over. My solution: only run the
simplifier in a clean, error-free type environment.

A downside of this is that fewer error messages are reported.
This makes me a bit sad, but I'm not sure how to avoid the problem.
Suggestions welcome.

This fixes #10817 and #10899. A knock-on effect is that we must
now remember locations of associated type defaults for error
messages during validity checking. This isn't too bad, but it
increases the size of the diff somewhat.

Test cases: indexed-types/should_fail/T108{17,99}

This makes two real changes:
 - Equalities like (a ~R [a]) really *are* insoluble. Previously,
   GHC refused to give up when an occurs check bit on a representational
   equality. But for datatypes, it really should bail.

 - Now, GHC will sometimes report an occurs check error (in cases above)
   for representational equalities. Previously, it never did.

This "fixes" #10715, where by "fix", I mean clarifies the error message.
It's unclear how to do more to fix that ticket.

Test cases: typecheck/should_fail/T10715{,b}

Thanks to Gabor Greif for spotting the mistake.

This fixes #10810 by cleaning up pretty-printing of constructor
declarations. This change also removes a (in my opinion) deeply
bogus orphan instance OutputableBndr [Located name], making
HsDecls now a non-orphan module. Yay all around.

Test case: th/T10810

The previous message was wrong, as pointed out by Jan Stolarek.

This fixes #10855.

This fixes #10811.

This is part of #10811. It removes the "family" keyword from
associated type family declarations, and it adds the "type"
keyword to associated type family defaults.

Reviewed by: austin

Differential Revision: https://phabricator.haskell.org/D1253

Test Plan: validate

Reviewers: simonpj, austin, bgamari

Reviewed By: austin, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1249

This gives a clearer indication as to what gets filled in
when. It was suggested by Richard on D1152.

Test Plan: ./validate

Reviewers: austin, goldfire, bgamari

Reviewed By: goldfire, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1245

To keep validates fast, we only one run one way.  But I think that
it's important for some tests to run them a few ways, just to
make sure functionality, e.g. the profiler, is working.  This commit
changes the logic so that any way specified in extra_ways is always
run for fast.  The big changes is now profiling tests are run on
validate.

I also made it so the G1 garbage collector tests only run on slow.
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: austin, thomie, bgamari

Reviewed By: austin, thomie, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1251

tcFamTyPats now must take information about the instantiation of any
class variables, when checking the instance of an associated type.

Getting this to work out required some unexpected refactoring in
TcDeriv. TcDeriv needs to look at class instances because of the
possibility of associated datatypes with `deriving` specs. TcDeriv
worked over the user-specified instances. But any data family instances
were already processed, and TcDeriv had no way of finding the rep
tycons. Indeed, TcDeriv *re-type-checked* any data family instances
in an attempt to rediscover what GHC already knew. So, this commit
introduces better tracking of compiled data families between TcInstDcls
and TcDeriv to streamline all of this.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: austin, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1250