I was seeing coercions like

   Nth 3 ((c2 -> c2) ; (c3 -> c4))

which made me realise that optCoercion was doing a bad job
of the (relatively new) FunCo.

In particular, opt_trans_rule needs a FunCo/FunCo case,
to go with the TyConAppCo/TyConAppCo case.  Easy.

No behavioural change, some coercions will get smaller

Summary:
This is a follow-up to @angerman 's refactoring for ELF
that happened with e5e8646
My previous commit a6675a9
corrected a typedef redefinition issue with GCC v4.4
(which is pervasive with RHEL 6). Now the problem has resurfaced.

Instead of dancing after the different compiler's pipe, I decided
to eliminate the typedefs altogether and refer to the struct
namespace explicitly.

Added a note to describe why typedefs are not
applied on customisable structs.

Reviewers: austin, bgamari, erikd, simonmar

Subscribers: rwbarton, thomie, angerman

Differential Revision: https://phabricator.haskell.org/D3527

Gracious me.  Ever since this patch

  commit 3744578
  Author: Jan Stolarek <jan.stolarek@p.lodz.pl>
  Date:   Fri Jul 11 13:54:45 2014 +0200

      Injective type families

TcRnMonad.askNoErrs has been wrong. It looked like this

   askNoErrs :: TcRn a -> TcRn (a, Bool)
   askNoErrs m
    = do { errs_var <- newTcRef emptyMessages
         ; res  <- setErrsVar errs_var m
         ; (warns, errs) <- readTcRef errs_var
         ; addMessages (warns, errs)
         ; return (res, isEmptyBag errs) }

The trouble comes if 'm' throws an exception in the TcRn monad.
Then 'errs_var is never read, so any errors are simply lost.

This mistake was then propgated into DsMonad.dsWhenNoErrs, where
it gave rise to Trac #13642.

Thank to Ryan for narrowing it down so sharply.

I did some refactoring, as usual.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13320

Differential Revision: https://phabricator.haskell.org/D3532

We gave up on typedefing {Section,ObjectCode}FormatInfo structs but
MachO never got the memo.

I left that out by mistake, and it apparently breaks at least one
existing plugin.

Reviewers: christiaanb, austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3518

Previously they were passed in the reverse order that they're specified
on the command line.

Add a haddock to frontendPluginOpts in DynFlags.hs.

Modify test frontend01 to cover the case of multiple -ffrontend-opt.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13632

Differential Revision: https://phabricator.haskell.org/D3520

There were broken links in users_guide for compact region.

  * Data-Compact -> GHC-Compact
  * compact-@LIBRARY_compact_VERSION@ ->
ghc-compact-@LIBRARY_compact_VERSION@

This commit is for ghc-8.2 branch.

Test Plan: build

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3521

There were old module names:

 * Data.Compact -> GHC.Compact
 * Data.Compact.Internal -> GHC.Compact

This commit is for ghc-8.2 branch.

Test Plan: build

Reviewers: austin, bgamari, hvr, erikd, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3522

The code in #11616 has been working for a while (ever since 8.0.1),
so let's add a regression test for it to put the nail in the coffin.

Test Plan: make test TEST=T11616

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #11616

Differential Revision: https://phabricator.haskell.org/D3531

Delete whitespace between brackets.  Because Github Flavored Markdown
was changed [1].

[1]: https://githubengineering.com/a-formal-spec-for-github-markdown/

Test Plan: build

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3534

Previously we would run all the monadic actions and then
combine their results. This caused problems if later actions
raised errors but earlier lookups suceeded. We only want to run later
lookups if the earlier ones fail.

Fixes #13622

Reviewers: RyanGlScott, austin, bgamari, simonpj

Reviewed By: simonpj

Subscribers: simonpj, rwbarton, thomie

GHC Trac Issues: #13622

Differential Revision: https://phabricator.haskell.org/D3515

Updates hpc submodule.

Reviewers: austin, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #11799

Differential Revision: https://phabricator.haskell.org/D3465

Previously we would force uf_is_value and friends to ensure that we didn't
retain a reference to the pre-tidying template, resulting in a space leak.
Instead, we now just reinitialize these fields (despite the fact that they
should not have changed). This may result in a bit more computation, but most of
the time we won't ever evaluate them anyways, so the damage shouldn't be so bad.

See #13564.

Simon pointed out that the zonk of the tyConKinds was redundant as tycon kinds
will never contain mutable variables. This allows us to remove tycon_kind.
Add a few commments clarifying the need to bring TyCon binders into scope before
typechecking bindings.

Summary:
Commit b4bdbe4 (the fix for #12156)
wound up being the fix for #12947 and #13640 as well. This adds regression
tests for the latter two tickets to keep them fixed.

Test Plan: make test TEST="T12947 T13640"

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #12947, #13640

Differential Revision: https://phabricator.haskell.org/D3528

Summary:
If you run `make test` on a non-Windows OS from a fresh build, the
testsuite will create an executable called `TimeMe` which `git` thinks is an
untracked file. Let's add it to `.gitignore` to avoid polluting the list of
untracked files.

Test Plan: Run `make test`, check if `TimeMe` is in the `git` untracked files

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3536

Commit eb55ec2 ended up fixing #13651, so
let's add a regression test for it.

Add a new (expect_broken) test T10600 that checks that the error:
Top-level bindings for unlifted types aren't allowed: is thrown when
compiling with -fno-code. This test currently fails because modules
compiled with -fno-code aren't desugared. There are several other errors
which can be thrown during desugaring that aren't tested for,
discoverable by grepping for "errDs".

Update .stderr files T8101 and T8101b. Presumably the compilation output
has changed slightly since they were written.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #10600, #8101

Differential Revision: https://phabricator.haskell.org/D3533

forkIOUnmasked has been deprecated for several years now. Update reference to
it. See #4858 and #5546.

There may be some subtlety I'm not seeing with the usage
of center vs centre. Otherwise this makes it more consistent
in the docs.
There's one instance in 8.0.2-notes.rst, but I'm not sure if
we want to modify it retroactively.

Test Plan: harbormaster?

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie, simonmar

Differential Revision: https://phabricator.haskell.org/D3548

Including #13665.

Previously OptCoercion would potentially change the type of UnivCo
coercions of the shape,
```
co :: TyCon arg1 ... argN ~ TyCon arg1' ... argN'
```
where the arities of the left and right applications differ. In this
case we
would try to zip the two argument lists, meaning that one would get
truncated.

One would think this could never happen since it implies we are
applying the
same TyCon to two different numbers of arguments. However, it does
arise in the
case of applications of the `Any` tycon, which arises from the
typechecker (in
`Data.Typeable.Internal`) where we end up with an `UnsafeCo`,
```
co :: Any (Any -> Any) Any ~ Any (Any -> Any)
```

Test Plan: Validate

Reviewers: simonpj, austin, goldfire

Reviewed By: simonpj

Subscribers: rwbarton, thomie

GHC Trac Issues: #13658

Differential Revision: https://phabricator.haskell.org/D3545

The single-threaded RTS shouldn't actually need to use CAS to
implement `casMutVar#`; there are no other threads to coordinate
with.

Reviewers: austin, bgamari, erikd, simonmar

Reviewed By: simonmar

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3544

This is two fold:

- We did not catch all ARM_ARCH_6 defines. Specifically not `6K` and
  `6KZ`, which is what llvm seems to use these days for
  `arm-none-linux-gnueabihf` (e.g. the triple that's used for raspbian
  as well). Without it, ghc assums we want to compile against some armv7
  system, which raspbian is not (it is armv6 for maximum compatibility
  across the pi family, compromising on using armv7 and up features).

- We stop forcing the -m and -arch flags on macOS. This is troublesome,
  as compiling for a 32bit system (e.g. raspberry pi, on a x86_64 macOS
  system results in the `-m64` flag being passed to to clang as well,
  which in turn figures out that you likely want 64bit, and rewrites
  your taret from `arm-none-linux-gnueabihf` to
  `aarch64-none-linux-gnueabihf`, which is definetly not what you want.

Reviewers: austin, hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, erikd

Differential Revision: https://phabricator.haskell.org/D3546

Reviewers: austin, goldfire, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, mpickering

GHC Trac Issues: #13211

Differential Revision: https://phabricator.haskell.org/D3543

The problem originates in TcPat.find_field_ty but I don't know how to
clearnly fix it.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13644

Differential Revision: https://phabricator.haskell.org/D3535

Using `IntSet` instead of `[Int]` is nicer since it gets rid of
appending to a list (in the backward case) and folding over it is
ordered.

I also added a comment about how `mkDepBlocks` works since its
behavior can be a bit surprising at first sight (it took me some time
to see that it's doing the right thing ;)

Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

Test Plan: ./validate

Reviewers: austin, bgamari, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3530

This reworks the HsSyn representation to make banged variable patterns
(e.g. !x = e) be represented as FunBinds instead of PatBinds, adding a flag to
FunRhs to record the bang.

Fixes #13594.

Reviewers: austin, goldfire, alanz, simonpj

Reviewed By: simonpj

Subscribers: simonpj, rwbarton, thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D3525

Always use the smart constructor!   Richard and I came across
this omission when looking at something else.

See Trac #13646 and the new
Note [Pattern bindings that bind no variables]

Simple refactor, no change in behaviour

I'd forgotten to reset this flag to True when dropping Derived
constraints, which led to Trac #13662.  Easily fixed.

This reverts commit b3da6a6 as it
reintroduces the original space leak.

This changes the linear lookup in a list to an efficient
lookup in an IntMap. The linear lookup effectively made
the algorithm quadratic, which for a test case that I have
(5000 modules) introduced significant slowdown.

I ran 3 experiments to estimate the impact of this:

"No-op", profiled, just `:load`: P146, `186s`
"before", profiled, `:load` followed by 10x `:r`: P147, `315s`
"after", profiled, `:load` followed by 10x `:r`: P148, `250s`

Going by the math of `(250-186)/(315-186) = 50%` this is a 2x improvement
on `:r`.

Test Plan: ./validate

Reviewers: simonmar, austin, bgamari

Reviewed By: simonmar

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3562

Every time we encountered a non-home module during the downsweep, we
were removing it from the finder cache.  That meant we were searching
the filesystem for every import, rather than once per downsweep.  The
fix is just to flush the finder cache before the downsweep, and
repopulate it for home modules that haven't changed.

Speeds up downsweep by about 25% on a large example I have.

Test Plan: Harbourmaster

Reviewers: bgamari, niteria, austin, erikd

Reviewed By: bgamari, niteria

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3554

This is rather annoying. I'd prefer to have a stable release to
use. However libffi-3.2.1 has been released November 12, 2014, and
libffi-4 is TBD. See also libffi/libffi#296

The core reason for this change is that llvm changed the supported
assembly to unified syntax, which libffi-3.2.1 does not use, and hence
fails to compile for arm with llvm. For refence, see the following
issue: libffi/libffi#191

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, snowleopard

Differential Revision: https://phabricator.haskell.org/D3349

This should be handled appropriately by a wrapper script around the compiler,
if one wants to insist on the specific linker to be used.  Otherwise this
breaks if the used compiler fails to understand this directive.

I believe that using a specific linker should be part of the compilers
toolchain, we delegate to and not hardcoded here in ghc.

Reviewers: dfeuer, erikd, hvr, austin, rwbarton, bgamari

Reviewed By: bgamari

Subscribers: snowleopard, davean, dfeuer, thomie, erikd

Differential Revision: https://phabricator.haskell.org/D3351

When we load non absolute pathed .so's this usually implies that we expect the
system to have them in place already, and hence we should not need to ship them.
Without the absolute path to the library, we are also unable to open and send
said library.  Thus we'll do library shipping only for libraries with absolute
paths.

Reviewers: austin, bgamari, simonmar

Reviewed By: simonmar

Subscribers: simonmar, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3469