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Signed-off-by: Austin Seipp <austin@well-typed.com>

This patch implements Pattern Synonyms (enabled by -XPatternSynonyms),
allowing y ou to assign names to a pattern and abstract over it.

The rundown is this:

  * Named patterns are introduced by the new 'pattern' keyword, and can
    be either *unidirectional* or *bidirectional*. A unidirectional
    pattern is, in the simplest sense, simply an 'alias' for a pattern,
    where the LHS may mention variables to occur in the RHS. A
    bidirectional pattern synonym occurs when a pattern may also be used
    in expression context.

  * Unidirectional patterns are declared like thus:

        pattern P x <- x:_

    The synonym 'P' may only occur in a pattern context:

        foo :: [Int] -> Maybe Int
        foo (P x) = Just x
        foo _     = Nothing

  * Bidirectional patterns are declared like thus:

        pattern P x y = [x, y]

    Here, P may not only occur as a pattern, but also as an expression
    when given values for 'x' and 'y', i.e.

        bar :: Int -> [Int]
        bar x = P x 10

  * Patterns can't yet have their own type signatures; signatures are inferred.

  * Pattern synonyms may not be recursive, c.f. type synonyms.

  * Pattern synonyms are also exported/imported using the 'pattern'
    keyword in an import/export decl, i.e.

        module Foo (pattern Bar) where ...

    Note that pattern synonyms share the namespace of constructors, so
    this disambiguation is required as a there may also be a 'Bar'
    type in scope as well as the 'Bar' pattern.

  * The semantics of a pattern synonym differ slightly from a typical
    pattern: when using a synonym, the pattern itself is matched,
    followed by all the arguments. This means that the strictness
    differs slightly:

        pattern P x y <- [x, y]

        f (P True True) = True
        f _             = False

        g [True, True] = True
        g _            = False

    In the example, while `g (False:undefined)` evaluates to False,
    `f (False:undefined)` results in undefined as both `x` and `y`
    arguments are matched to `True`.

For more information, see the wiki:

    https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms
    https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms/ImplementationReviewed-by: Simon Peyton Jones <simonpj@microsoft.com>
Signed-off-by: Austin Seipp <austin@well-typed.com>

(artificial test cases are so nice: 90.7% improvement!)

by passing the FamInstEnvs all the way down. This closes #7619.

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

On FreeBSD, /usr/lib has to be added to the library path on linking when
libthr is needed but -nostdlib is used (which is the case when the -prof
and -threaded flags are combined).

All actively supported releases (8.4-RELEASE, 9.2-RELEASE and the
upcoming 10.0-RELEASE) now support resolution of $ORIGIN properly.

Haddock no longer has a generated parser, so we don't need it in the
sdist and we certainly don't want to check for it in the ./configure
script (as that would be bogus.)
Signed-off-by: Austin Seipp <austin@well-typed.com>

See Trac #8672

Fixes Trac #8674

The former adds a newline at the end (restoring the previous behaviour)
while the latter does not (which previously happened by turning the
thuing into a string and only then printing it).

Instead of first checking whether splitting is useful, and then firing
up the worker-wrapper-machinery, which will do the same checks again, we
now simply generate a worker and wrapper, and while doing so keep track
of whether what we did was in any way useful.

So now there is only one place left where we decide whether we want to
do w/w, and that place has access to more information, in particular the
actual types at hand.

these functions were almost equal, and neither validate nor nofib show
any difference replacing one by the other. So lets simplify this.
(This also prepares for a refactoring that will get rid of
worthSplittingArgDmd completely.)

This should contain a fix that addresses the Solaris build breakage
(see #8670)
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

By using the constant-folder to reduce it to an integer.

We occasionally need to reserve some temporary memory in a primop for
passing to a foreign function.  We've been using the stack for this,
but when we moved to high-level Cmm it became quite fragile because
primops are in high-level Cmm and the stack is supposed to be under
the control of the Cmm pipeline.

So this change puts things on a firmer footing by adding a new Cmm
construct 'reserve'.  e.g. in decodeFloat_Int#:

    reserve 2 = tmp {

      mp_tmp1  = tmp + WDS(1);
      mp_tmp_w = tmp;

      /* Perform the operation */
      ccall __decodeFloat_Int(mp_tmp1 "ptr", mp_tmp_w "ptr", arg);

      r1 = W_[mp_tmp1];
      r2 = W_[mp_tmp_w];
    }

reserve is described in CmmParse.y.

Unfortunately the argument to reserve must be a compile-time constant.
We might have to extend the parser to allow expressions with
arithmetic operators if this is too restrictive.

Note also that the return instruction for the procedure must be
outside the scope of the reserved stack area, so we have to extract
the values from the reserved area before we close the scope.  This
means some more local variables (r1, r2 in the example above).  The
generated code is more or less identical to what we had before though.

Presumably broken by an earlier change, anyone know which one?

in which case it is a wontfix (see #8569)

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

Clang warns about implicit return values by default.
Signed-off-by: Austin Seipp <austin@well-typed.com>

This fixes a large majority of the testsuite failures on Mavericks with
Clang.
Signed-off-by: Austin Seipp <austin@well-typed.com>

Signed-off-by: Austin Seipp <austin@well-typed.com>

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

When printing an update frame in printClosure(), it will not print
the unspecific UPDATE_FRAME, instead it prints BH_UPDATE_FRAME,
NORMAL_UPDATE_FRAME or MARKED_UPDATE_FRAME.
Signed-off-by: Austin Seipp <austin@well-typed.com>

Signed-off-by: Austin Seipp <austin@well-typed.com>

These new versions get rid of AMP warnings
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

After some discussion on ghc-devs@ and elsewhere, it seemed favorable to
make this change as type holes don't let any invalid programs though,
they merely change what the compiler reports in case of certain errors
(namely unbound occurrences, or _ appearing on a LHS.)

Now, the warning mechanism is controlled by -f[no-]warn-type-errors,
just like any other regular warning. Again, on by default.

The documentation and tests have been updated accordingly.
Signed-off-by: Austin Seipp <austin@well-typed.com>