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Add a DEBUG catch-all case in do_expr.

Wibble in hi-boot file

Behave better in decode_escape failure

hardtop: newer versions of bash (and ash) have 'pwd' return paths
of the following form: /cygdrive/<drive>/<rest>

Transform these into <drive>:/<rest>, as that format is easier to
work with under mingw.

make prev. commit compile on non-win32 boxes

removed ToDo comment + braino

Rearranged how the virtual timer 'subsystem' is brought up and down:

* "int startVirtTimer(nat ms)" now starts the vtimer/ticker.
* "int stopVirtTimer()" shuts down the ticker.

i.e., removed install_vtalrm_handler() and initialize_virtual_timer().

track 5.03's change to PrelHandle.fillReadBuffer

have happy-inplace rule depend on glafp-utils/

make it work on non-mingw platforms

Make the IO implementation work with WinSock once again.

When creating sockets with WinSock, you don't get back
a file descriptor, but a SOCKET (which just so happens
to map to the same type as a 'normal' file descriptor).
This SOCKET value cannot be used with the CRT ops
read(), write(), close(), but you have to use the
socket-specific operations (recv(), send(), and closesocket(),
respectively) instead.

To keep track of this distinction between file and
socket file descriptors, the following changes were
made:

* a Handle__ has got a new field, haIsStream, which is True
  for sockets / streams.
  (this field is essentially unused in non-Win32 settings,
   but I decided not to conditionalise its presence).
* PrelHandle.openFd now takes an extra (Maybe FDType) argument,
  which lets you force what type of FD we're converting into
  a Handle (this is crucial for WinSock SOCKETs, since we don't
  want to attempt fstat()ing them).

Fixes breakage that was introduced with May 2001 (or earlier)
rewrite of the IO layer. This commit build upon recent IO changes
to HEAD, so merging it to STABLE will require importing those
changes too (I'll let others be the judge whether this should
be done or not).

win32 only - provide closeFd, which closes a file descriptor, be it of
file or socket ilk.

Profiling cleanup.

This commit eliminates some duplication in the various heap profiling
subsystems, and generally centralises much of the machinery.  The key
concept is the separation of a heap *census* (which is now done in one
place only instead of three) from the calculation of retainer sets.
Previously the retainer profiling code also did a heap census on the
fly, and lag-drag-void profiling had its own census machinery.

Value-adds:

   - you can now restrict a heap profile to certain retainer sets,
     but still display by cost centre (or type, or closure or
     whatever).

   - I've added an option to restrict the maximum retainer set size
     (+RTS -R<size>, defaulting to 8).

   - I've cleaned up the heap profiling options at the request of
     Simon PJ.  See the help text for details.  The new scheme
     is backwards compatible with the old.

   - I've removed some odd bits of LDV or retainer profiling-specific
     code from various parts of the system.

   - the time taken doing heap censuses (and retainer set calculation)
     is now accurately reported by the RTS when you say +RTS -Sstderr.

Still to come:

   - restricting a profile to a particular biography
     (lag/drag/void/use).  This requires keeping old heap censuses
     around, but the infrastructure is now in place to do this.

fdType: clarify that this op will fail with non-file handles/descriptors
        under Win32.

Use an arena internally to allocate hash bucket cells instead of the
current home-brewed combination of malloc/free and a free list.

We still allocate hash table segments using malloc/free because these
are large (4k by default) and might interact badly with the blockish
nature of the arena allocator.

In the Win32 build, don't call initProfTimer unless PROFILING
is on.  This mirrors the Unix deal.   Indeed initProfTimer
isn't defined if PROFILING is on.

I don't know how this works for anyone else on Win32!
Sigbjorn: have I done this right, or am I misunderstanding?

Complete previous tcAddImportedIdInfo commit

Improve error reporting

Comments only

--------------------------------------
	Finally get rid of tcAddImportedIdInfo
	--------------------------------------

TcEnv.tcAddImportedIdInfo is a notorious source of space leaks.
Simon M got rid of the need for it on default methods.
This commit gets rid of the need for it for dictionary function Ids,
and finally nukes the beast altogether. Hurrah!

The change really involves putting tcInterfaceSigs *before*
tcInstDecls1, so that any imported DFunIds are in the typechecker's
environment before we get to tcInstDecls.

Add missing files for Rank-N commit

----------------------
	Implement Rank-N types
	----------------------

This commit implements the full glory of Rank-N types, using
the Odersky/Laufer approach described in their paper
	"Putting type annotations to work"

In fact, I've had to adapt their approach to deal with the
full glory of Haskell (including pattern matching, and the
scoped-type-variable extension).  However, the result is:

* There is no restriction to rank-2 types.  You can nest forall's
  as deep as you like in a type.  For example, you can write a type
  like
	p :: ((forall a. Eq a => a->a) -> Int) -> Int
  This is a rank-3 type, illegal in GHC 5.02

* When matching types, GHC uses the cunning Odersky/Laufer coercion
  rules.  For example, suppose we have
	q :: (forall c. Ord c => c->c) -> Int
  Then, is this well typed?
	x :: Int
	x = p q
  Yes, it is, but GHC has to generate the right coercion.  Here's
  what it looks like with all the big lambdas and dictionaries put in:

	x = p (\ f :: (forall a. Eq a => a->a) ->
		 q (/\c \d::Ord c -> f c (eqFromOrd d)))

  where eqFromOrd selects the Eq superclass dictionary from the Ord
  dicationary:		eqFromOrd :: Ord a -> Eq a


* You can use polymorphic types in pattern type signatures.  For
  example:

	f (g :: forall a. a->a) = (g 'c', g True)

  (Previously, pattern type signatures had to be monotypes.)

* The basic rule for using rank-N types is that you must specify
  a type signature for every binder that you want to have a type
  scheme (as opposed to a plain monotype) as its type.

  However, you don't need to give the type signature on the
  binder (as I did above in the defn for f).  You can give it
  in a separate type signature, thus:

	f :: (forall a. a->a) -> (Char,Bool)
	f g = (g 'c', g True)

  GHC will push the external type signature inwards, and use
  that information to decorate the binders as it comes across them.
  I don't have a *precise* specification of this process, but I
  think it is obvious enough in practice.

* In a type synonym you can use rank-N types too.  For example,
  you can write

	type IdFun = forall a. a->a

	f :: IdFun -> (Char,Bool)
	f g = (g 'c', g True)

  As always, type synonyms must always occur saturated; GHC
  expands them before it does anything else.  (Still, GHC goes
  to some trouble to keep them unexpanded in error message.)


The main plan is as before.  The main typechecker for expressions,
tcExpr, takes an "expected type" as its argument.  This greatly
improves error messages.  The new feature is that when this
"expected type" (going down) meets an "actual type" (coming up)
we use the new subsumption function
	TcUnify.tcSub
which checks that the actual type can be coerced into the
expected type (and produces a coercion function to demonstrate).

The main new chunk of code is TcUnify.tcSub.  The unifier itself
is unchanged, but it has moved from TcMType into TcUnify.  Also
checkSigTyVars has moved from TcMonoType into TcUnify.
Result: the new module, TcUnify, contains all stuff relevant
to subsumption and unification.

Unfortunately, there is now an inevitable loop between TcUnify
and TcSimplify, but that's just too bad (a simple TcUnify.hi-boot
file).


All of this doesn't come entirely for free.  Here's the typechecker
line count (INCLUDING comments)
	Before	16,551
	After	17,116

Added a new section that describes how GHC defines its hardwired knowledge
about primitives and special prelude definitions.

Tidyup - only declare&use half-a-dozen prof-only global variables
when PROFILING.

Retainer/LDV changes.

The recent prof-related commit forgot to include RtsFlags.h, methinks.
But, modulo trivia, I'm reasonably sure that this commit mirrors
whatever mods that unchecked-in file contains.

extend the scope of the doNothing() macro; can now be used in Stg headers

Put spaces round %, in preparation for splittable name supplies

unbreak tcModule.

Use (DefMeth Name) rather than (DefMeth Id) in ClassOpItem.  This not
only eliminates a space leak, because Names generally hold on to much
less stuff than Ids, but also turns out to be a minor cleanup.

Replace a lazy pattern match in tcGetInstLoc with a strict one (fixes
a space leak).

Adorn various constructor fields with strictness annotations - this
fixes at least one space leak, in the mi_usages field of a ModIface.

Collect up _scc_ expressions on the right hand side of a closure
definition and attach them directly to the closure using PushCC-type
cost centres, so that the allocation of the closure gets attributed to
the right place.

Fix a long-standing bug in the cost attribution of cost-center stacks.
The problem case is this:

	let z = _scc_ "z" f x
	in ... z ...

previously we were attributing the cost of allocating the closure 'z'
to the enclosing cost center stack (CCCS), when it should really be
attributed to "z":CCCS.  The effects are particularly visible with
retainer profiling, because the closure retaining 'f' and 'x' would
show up with the wrong CCS attached.

To fix this, we need a new form of CCS representation internally:
'PushCC CostCentre CostCentreStack' which subsumes (and therefore
replaces) SingletonCCS.  SingletonCCS is now represented by 'PushCC cc
NoCCS'.

The CCS argument to SET_HDR may now be an arbitrary expression, such
as PushCostCentre(CCCS,foo_cc), as may be the argument to CCS_ALLOC().
So we combine SET_HDR and CCS_ALLOC into a single macro, SET_HDR_, to
avoid repeated calls to PushCostCentre().

Call LDV_ENTER() on entry to a constructor in profiling mode.

Call LDV_ENTER() on entry to a thunk or function in profiling mode.

Add
	ldvEnter :: Code

for LDV profiling: it records that the closure pointed to by R1 has
just been entered.

We don't need to consider Hp as a volatile register across C calls; it
is already saved by the CALLER_SAVES_SYSTEM macro.

Fix compilation problems with Stats.c in the !DEBUG case.

Omit GC and SYSTEM from the cost centre summary at the top of the profile.

Add rts_getThreadId to the Linker's built in symbol table