Now, the threaded RTS also includes SMP support.  The -smp flag is a
synonym for -threaded.  The performance implications of this are small
to negligible, and it results in a code cleanup and reduces the number
of combinations we have to test.

rather than recordMutableGen(), the former works better in SMP

When the RTS is idle, as detected by the timer signal, instead of
prodding capabilities from the signal handler (which is not guaranteed
to work - pthread_cond_signal() can't be called from signal handlers),
create a new thread to do it.

GHC 6.4 implements a rather relaxed version of the Coverage Condition
which is actually too relaxed: the compiler can get into an infinite loop
as a result.

This commit fixes the problem (see Note [Coverage condition] in FunDeps.lhs)
and documents the change.

I also took the opportunity to add documentation about functional dependencies,
taken from the Hugs manual with kind permission of Mark Jones

We always assign to BaseReg on return from resumeThread(), but in
cases where BaseReg is not an lvalue (eg. unreg) we need to disable
this assigment.  See comments for more details.

Tidying up to Ross's  patch, plus adding documenation for it.

With -fglasgow-exts but not -fallow-undecidable-instances, GHC 6.4
requires that instances be of the following form:

 (1) each assertion in the context must constrain distinct variables
     mentioned in the head, and

 (2) at least one argument of the head must be a non-variable type.

This patch replaces these rules with the requirement that each assertion
in the context satisfy

 (1) no variable has more occurrences in the assertion than in the head, and

 (2) the assertion has fewer constructors and variables (taken together
     and counting repetitions) than the head.

This allows all instances permitted by the old rule, plus such instances as

       instance C a
       instance Show (s a) => Show (Sized s a)
       instance (Eq a, Show b) => C2 a b
       instance C2 Int a => C3 Bool [a]
       instance C2 Int a => C3 [a] b
       instance C4 a a => C4 [a] [a]

but still ensures that under any substitution assertions in the context
will be smaller than the head, so context reduction must terminate.

This is probably the best we can do if we consider each instance in
isolation.

This commit fixes a bug in 6.4.1 and the HEAD.  Consider this code,
recorded **in an interface file**

    \(x::a) -> case y of 
	         MkT -> case x of { True -> ... }
(where MkT forces a=Bool)

In the "case x" we need to know x's type, because we use that
to find which module to look for "True" in. x's type comes from
the envt, so we must refine the envt.  

The alternative would be to record more info with an IfaceCase,
but that would change the interface file format.

(This stuff will go away when we have proper coercions.)
	

Fixes #660

We had to bite the bullet here and add an extra word to every thunk,
to enable running ordinary libraries on SMP.  Otherwise, we would have
needed to ship an extra set of libraries with GHC 6.6 in addition to
the two sets we already ship (normal + profiled), and all Cabal
packages would have to be compiled for SMP too.  We decided it best
just to take the hit now, making SMP easily accessible to everyone in
GHC 6.6.

Incedentally, although this increases allocation by around 12% on
average, the performance hit is around 5%, and much less if your inner
loop doesn't use any laziness.

This patch adds completion support to GHCi when readline is being
used.  Completion of identifiers (in scope only, but including
qualified identifiers) in expressions is provided.  Also, completion
of commands (:cmd), and special completion for certain commands
(eg. module names for the :module command) are also provided.

This commit adds bang-patterns, 
	enabled by -fglasgow-exts or -fbang-patterns
	diabled by -fno-bang-patterns

The idea is described here
	http://haskell.galois.com/cgi-bin/haskell-prime/trac.cgi/wiki/BangPatterns

We must record the type of a TuplePat after typechecking, just like a ConPatOut,
so that desugaring works correctly for GADTs. See comments with the declaration
of HsPat.TuplePat, and test gadt15

Also extend the parser.

	MERGE TO STABLE

For a long time (2002!) the CPR analysis done by
dmdAnalTopRhs has been bogus.  In particular, it's possible
for a newtype constructor to look CPR-ish when it simply isn't.

This fixes it.  Test is stranal/newtype