This adds a regression test for the original program in #14040.

This does not fix #14040 entirely, though, as the program in
https://ghc.haskell.org/trac/ghc/ticket/14040#comment:2 still
panics, so there is more work to be done there.

(cherry picked from commit be1ca0e4)

Trac #13032 pointed out that we sometimes generate unused
bindings for Givens, and (worse still) we can't always discard
them later (we don't drop a case binding unless we can prove
that the scrutinee is non-bottom.

It looks as if this may be a major reason for the performace
problems in #14338 (see comment:29).

This patch fixes the problem at source, by pruning away all the
dead Givens.  See Note [Delete dead Given evidence bindings]

Remarkably, compiler allocation falls by 23% in
perf/compiler/T12227!

I have not confirmed whether this change actualy helps with

(cherry picked from commit 954cbc7c)

This rather subtle patch fixes Trac #14584.  The problem was
that we'd allowed a coercion, bound in a nested scope, to escape
into an outer scope.

The main changes are

* TcSimplify.floatEqualities takes more care when floating
  equalities to make sure we don't float one out that mentions
  a locally-bound coercion.
  See Note [What prevents a constraint from floating]

* TcSimplify.emitResidualConstraints (which emits the residual
  constraints in simplifyInfer) now avoids burying the constraints
  for escaping CoVars inside the implication constraint.

* Since I had do to this stuff with CoVars, I moved the
  fancy footwork about not quantifying over CoVars from
  TcMType.quantifyTyVars to its caller
  TcSimplify.decideQuantifiedTyVars.  I think its other
  callers don't need to worry about all this CoVar stuff.

This turned out to be surprisigly tricky, and took me a solid
day to get right.  I think the result is reasonably neat, though,
and well documented with Notes.

(cherry picked from commit f5cf9d1a)

In fixing Trac #14584 I found that it would be /much/ more
convenient if a "hole" in a coercion (much like a unification
variable in a type) acutally had a CoVar associated with it
rather than just a Unique.  Then I can ask what the free variables
of a coercion is, and get a set of CoVars including those
as-yet-un-filled in holes.

Once that is done, it makes no sense to stuff coercion holes
inside UnivCo.  They were there before so we could know the
kind and role of a "hole" coercion, but once there is a CoVar
we can get that info from the CoVar.  So I removed HoleProv
from UnivCoProvenance and added HoleCo to Coercion.

In summary:

* Add HoleCo to Coercion and remove HoleProv from UnivCoProvanance

* Similarly in IfaceCoercion

* Make CoercionHole have a CoVar in it, not a Unique

* Make tyCoVarsOfCo return the free coercion-hole variables
  as well as the ordinary free CoVars.  Similarly, remember
  to zonk the CoVar in a CoercionHole

We could go further, and remove CoercionHole as a distinct type
altogther, just collapsing it into HoleCo.  But I have not done
that yet.

(cherry picked from commit a492af06)

This fixes Trac #14479.  Not difficult.

See Note [Quantification and partial signatures] Wrinkle 4,
in TcSimplify.

(cherry picked from commit 72938f58)

This patch fixes two bugs in the treatment of SigTvs at the
kind level:

- We should always generalise them, never default them
  (Trac #14555, #14563)

- We should check if they get unified with each other
  (Trac #11203)

Both are described in TcHsType
   Note [Kind generalisation and SigTvs]

(cherry picked from commit 8361b2c5)

This refactoring

* Renames kcHsTyVarBndrs to kcLHsQTyVars,
  which is more truthful. It is only used in getInitialKind.

* Pulls out bind_telescope from that function, and calls it
  kcLHsTyVarBndrs, again to reflect its argument

* Uses the new kcLHsTyVarBndrs in kcConDecl, where the old
  function was wild overkill.

There should not be any change in behaviour

(cherry picked from commit de204409)

Matthias Treydte authored 7 years ago and Ben Gamari committed 7 years ago

when read notifications are requested, too (#13903)

Signed-off-by: Matthias Treydte <mt@waldheinz.de>

KQueue: Drop Bits/FiniteBits instances for Filter as they are really
constants whose bits should not be fiddled with

Signed-off-by: Matthias Treydte <mt@waldheinz.de>

Reviewers: austin, hvr, bgamari

Reviewed By: bgamari

Subscribers: gridaphobe, kazu_yamamoto, rwbarton, thomie

GHC Trac Issues: #13903

Differential Revision: https://phabricator.haskell.org/D3692

(cherry picked from commit 6c3eafb3)

Summary:
`GeneralizedNewtypeDeriving` generates calls to `coerce`
which take visible type arguments. These types must be produced by
way of `typeToLHsType`, which converts a `Type` to an `LHsType`.
However, `typeToLHsType` was leaving off important kind information
when a `Type` contained a poly-kinded tycon application, leading to
incorrectly generated code in #14579.

This fixes the issue by tweaking `typeToLHsType` to generate
explicit kind signatures for tycon applications. This makes the
generated code noisier, but at least the program from #14579 now
works correctly.

Test Plan: make test TEST=T14579

Reviewers: simonpj, bgamari

Reviewed By: simonpj

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #14579

Differential Revision: https://phabricator.haskell.org/D4264

(cherry picked from commit 649e7772)

Summary:
The `HsType` pretty-printer does not automatically insert
parentheses where necessary for type applications, so a function
`isCompoundHsType` was created in D4056 towards this purpose.
However, it was not used in as many places as it ought to be,
resulting in #14578.

Test Plan: make test TEST=T14578

Reviewers: alanz, bgamari, simonpj

Reviewed By: alanz, simonpj

Subscribers: simonpj, rwbarton, thomie, carter

GHC Trac Issues: #14578

Differential Revision: https://phabricator.haskell.org/D4266

(cherry picked from commit 1bd91a7a)

Summary: To be in line with the other typeNatTyCons

Reviewers: bgamari, RyanGlScott

Reviewed By: RyanGlScott

Subscribers: RyanGlScott, rwbarton, thomie, carter

GHC Trac Issues: #14632

Differential Revision: https://phabricator.haskell.org/D4284

(cherry picked from commit fb78b0d2)

Commit fa8035e3 added `Div`
and `Mod` type families to `GHC.TypeNats`. However, they did not add
the corresponding fixities! Currently, we have that both `div` and
`mod` (at the value level) are `infixl 7`, so we should adopt the
same fixities for the type-level `Div` and `Mod` as well.

Test Plan: It compiles

Reviewers: hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #14640

Differential Revision: https://phabricator.haskell.org/D4291

(cherry picked from commit 303106d5)

Commit 714bebff removed
a check in the bytecode compiler that caught illegal uses of unboxed
tuples (and now sums) in case alternatives, which causes the program
in #14608 to panic. This restores the check (using modern,
levity-polymorphic vocabulary).

Test Plan: make test TEST=T14608

Reviewers: hvr, bgamari, dfeuer, simonpj

Reviewed By: dfeuer, simonpj

Subscribers: simonpj, rwbarton, thomie, carter

GHC Trac Issues: #14608

Differential Revision: https://phabricator.haskell.org/D4276

(cherry picked from commit ecff651f)

Tamar Christina authored 7 years ago and Ben Gamari committed 7 years ago

This calls out to the Win32 API `GetTempFileName` to generate
a temporary file. Using `uUnique = 0` guarantees that the file
we get back is unique and the file is "reserved" by creating it.

Test Plan:
./validate

I can't think of any sensible tests that shouldn't run for a while
to verify. So the example in #10731 was ran for a while and no
collisions in new code

Reviewers: hvr, bgamari, erikd

Reviewed By: bgamari

Subscribers: RyanGlScott, rwbarton, thomie, carter

GHC Trac Issues: #10731

Differential Revision: https://phabricator.haskell.org/D4278

(cherry picked from commit 46287af0)

Richard Eisenberg authored 7 years ago and Ben Gamari committed 7 years ago

Previously, we were inexplicably not applying an instantiating
substitution to arguments in non-prenex types. It's amazing this
has been around for so long! I guess there aren't a lot of non-prenex
types around.

test case: typecheck/should_fail/T14618

(cherry picked from commit 722a6584)

(cherry picked from commit e237e1f1)

Split-sections unfortunately isn't yet working.

Prior to 8.0.2 MultiWayIf syntax required that the -> token be indented relative
to the guard. See #10807.

[skip ci]

(cherry picked from commit 4d99a665)

[skip ci]

(cherry picked from commit 00565677)

carlostome authored 7 years ago and Ben Gamari committed 7 years ago

We filter the complete patterns given in a COMPLETE set to only those that
subsume the type we are matching. Otherwise we end up introducing an ill-typed
equation into the overlap checking, provoking a crash. This was the cause of
Trac #14135.

Reviewers: austin, bgamari, mpickering, gkaracha, simonpj, RyanGlScott,
carlostome

Reviewed By: bgamari

Subscribers: carter, dfeuer, RyanGlScott, goldfire, rwbarton, thomie

GHC Trac Issues: #14135

Differential Revision: https://phabricator.haskell.org/D3981

(cherry picked from commit 16c7d9dc)

Nathan Collins authored 7 years ago and Ben Gamari committed 7 years ago

This fixes Issue #12372: documentation for Control.Monad.guard not
useful after AMP.

Reviewers: hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4258

(cherry picked from commit 6847c6bf)

Because in recent RHEL7 suddenly locales like `bokmål` pop up, which
screw up reading-in of ASCII strings a line later. This additional
criterion reliably eliminates those unicode characters.

(cherry picked from commit abd5db60)

* Add a new flag, `-fignore-optim-changes`, allowing them to avoid
  recompilation if the only changes are to the `-O` level or to
  flags controlling optimizations.

* When `-fignore-optim-changes` is *off*, recompile when optimization
  flags (e.g., `-fno-full-laziness`) change. Previously, we ignored
  these unconditionally when deciding whether to recompile a module.

Reviewers: austin, bgamari, simonmar

Reviewed By: simonmar

Subscribers: duog, carter, simonmar, rwbarton, thomie

GHC Trac Issues: #13604

Differential Revision: https://phabricator.haskell.org/D4123

(cherry picked from commit 708ed9ca)

Ben Gamari authored 7 years ago and Ben Gamari committed 7 years ago

This was presumably a vestige of the days when the profiled RTS couldn't
run threaded. Fixes #14545.

Test Plan: simonmar

Reviewers: erikd, simonmar

Reviewed By: simonmar

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #14545

Differential Revision: https://phabricator.haskell.org/D4245

(cherry picked from commit 4bfff7a5)

Simon Marlow authored 7 years ago and Ben Gamari committed 7 years ago

open() can sometimes take a long time, for example on NFS or FUSE
filesystems.  We recently had a case where open() was taking multiple
seconds to return for a (presumably overloaded) FUSE filesystem, which
blocked GC and caused severe issues.

Test Plan: validate

Reviewers: niteria, bgamari, nh2, hvr, erikd

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #13296

Differential Revision: https://phabricator.haskell.org/D4239

(cherry picked from commit cafe9834)

It will remain a submodule until we are ready to merge Hadrian into the
tree.

Sadly subtrees haven't worked quite as well as we would have liked for
developers. See Hadrian #440.

Updates haddock dsubmodule

The LaTeX produced by this previously failed to compile. Changing the first cell
of the row from an inline to a paragraph fixes this. Then I noticed that the
table overflowed the page. This is fixed by applying the longtable class.

This was scheduled to happen for 8.2, it looks like it will actually
happen in 8.4.

Matching with the `Con` and `Con'` patterns can reveal evidence
that the type in question is *not* an application. This can help
the pattern checker.

Reviewers: austin, hvr, bgamari

Reviewed By: bgamari

Subscribers: carter, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D4139

Cache `TypeRep k` in each `TrApp` or `TrTyCon` constructor of
`TypeRep (a :: k)`. This makes `typeRepKind` cheap.

With this change, we won't need any special effort to deserialize
typereps efficiently. The downside, of course, is that we make
`TypeRep`s slightly larger.

Reviewers: austin, hvr, bgamari, simonpj

Reviewed By: bgamari, simonpj

Subscribers: carter, simonpj, rwbarton, thomie

GHC Trac Issues: #14254

Differential Revision: https://phabricator.haskell.org/D4085

Add support for injecting runtime calls to `trace` in `DsM`. This
allows the desugarer to add compile-time information to a runtime
trace.

Reviewers: austin, hvr, bgamari

Reviewed By: bgamari

Subscribers: carter, thomie, rwbarton

Differential Revision: https://phabricator.haskell.org/D4162

Summary:
Previously, we attempted to lookup 'hole' packages for
include directories; this obviously is not going to work.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Test Plan: validate

Reviewers: ekmett, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #14525

Differential Revision: https://phabricator.haskell.org/D4234

Summary:
Suppose that you are typechecking A.hs, which transitively imports,
via B.hs, A.hs-boot.  When we poke on B.hs and discover that it
has a reference to a type from A, what TyThing should we wire
it up with?  Clearly, if we have already typechecked A, we
should use the most up-to-date TyThing: the one we freshly
generated when we typechecked A.  But what if we haven't typechecked
it yet?

For the longest time, GHC adopted the policy that this was
*an error condition*; that you MUST NEVER poke on B.hs's reference
to a thing defined in A.hs until A.hs has gotten around to checking
this.  However, actually ensuring this is the case has proven
to be a bug farm.  The problem was especially poignant with
type family consistency checks, which eagerly happen before
any typechecking takes place.

This patch takes a different strategy: if we ever try to access
an entity from A which doesn't exist, we just fall back on the
definition of A from the hs-boot file.  This means that you may
end up with a mix of A.hs and A.hs-boot TyThings during the
course of typechecking.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Test Plan: validate

Reviewers: simonpj, bgamari, austin, goldfire

Subscribers: thomie, rwbarton

GHC Trac Issues: #14396

Differential Revision: https://phabricator.haskell.org/D4154