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Fix problem with inline foreign-call changes yesterday.  Foreign call
args sometimes have to be modified using shimFCallArg - nowadays this
is done at code generation time, whereas it used to be done at
pretty-printing time.

Allow case-of-unsafe-ccall to compile to straight-line code, like it
used to.  This has already been fixed on the backend-hacking-branch,
but I'm doing it here so that it can be merged into the STABLE branch,
where it will help to work around a bug.

The bug is in CgExpr.lhs:primRetUnboxedTuple, which picks temporaries
to assign the result of a ccall to.  The Cg monad doesn't have a uniq
supply (in the HEAD), so we always pick the same temporaries.  This
leads to clashes in complex function with multiple ccalls.  Again,
this is already fixed in the backend-hacking-branch.  I don't see an
easy fix for this bug.

The compilation of case-of-unsafe-ccall doesn't suffer from this
problem, and it will help work around some cases of the bug, so I'm
going to merge this onto the STABLE branch after some testing.

ClosureInfo.might_be_a_function: this predicate wasn't taking into
account abstract types, which might also hide functions underneath.

Fixes broken compiler when compiled without -O.

Add dependency on GHC.TopHandler if this is the main module.

Add accurate source location annotations to HsSyn
-------------------------------------------------

Every syntactic entity in HsSyn is now annotated with a SrcSpan, which
details the exact beginning and end points of that entity in the
original source file.  All honest compilers should do this, and it was
about time GHC did the right thing.

The most obvious benefit is that we now have much more accurate error
messages; when running GHC inside emacs for example, the cursor will
jump to the exact location of an error, not just a line somewhere
nearby.  We haven't put a huge amount of effort into making sure all
the error messages are accurate yet, so there could be some tweaking
still needed, although the majority of messages I've seen have been
spot-on.

Error messages now contain a column number in addition to the line
number, eg.

   read001.hs:25:10: Variable not in scope: `+#'

To get the full text span info, use the new option -ferror-spans.  eg.

   read001.hs:25:10-11: Variable not in scope: `+#'

I'm not sure whether we should do this by default.  Emacs won't
understand the new error format, for one thing.

In a more elaborate editor setting (eg. Visual Studio), we can arrange
to actually highlight the subexpression containing an error.  Eventually
this information will be used so we can find elements in the abstract
syntax corresponding to text locations, for performing high-level editor
functions (eg. "tell me the type of this expression I just highlighted").

Performance of the compiler doesn't seem to be adversely affected.
Parsing is still quicker than in 6.0.1, for example.

Implementation:

This was an excrutiatingly painful change to make: both Simon P.J. and
myself have been working on it for the last three weeks or so.  The
basic changes are:

 - a new datatype SrcSpan, which represents a beginning and end position
   in a source file.

 - To reduce the pain as much as possible, we also defined:

      data Located e = L SrcSpan e

 - Every datatype in HsSyn has an equivalent Located version.  eg.

      type LHsExpr id = Located (HsExpr id)

   and pretty much everywhere we used to use HsExpr we now use
   LHsExpr.  Believe me, we thought about this long and hard, and
   all the other options were worse :-)


Additional changes/cleanups we made at the same time:

  - The abstract syntax for bindings is now less arcane.  MonoBinds
    and HsBinds with their built-in list constructors have gone away,
    replaced by HsBindGroup and HsBind (see HsSyn/HsBinds.lhs).

  - The various HsSyn type synonyms have now gone away (eg. RdrNameHsExpr,
    RenamedHsExpr, and TypecheckedHsExpr are now HsExpr RdrName,
    HsExpr Name, and HsExpr Id respectively).

  - Utilities over HsSyn are now collected in a new module HsUtils.
    More stuff still needs to be moved in here.

  - MachChar now has a real Char instead of an Int.  All GHC versions that
    can compile GHC now support 32-bit Chars, so this was a simplification.

GC dead code.

GC some dead code.  In some places, I left useful-looking but
currently unused definitions in place, surrounded by #ifdef UNUSED
... #endif.

This commit does a long-overdue tidy-up

* Remove PprType (gets rid of one more bunch of hi-boot files)

* Put pretty-printing for types in TypeRep

* Make a specialised pretty-printer for Types, rather than
  converting to IfaceTypes and printing those

-------------------------
		GHC heart/lung transplant
		-------------------------

This major commit changes the way that GHC deals with importing
types and functions defined in other modules, during renaming and
typechecking.  On the way I've changed or cleaned up numerous other
things, including many that I probably fail to mention here.

Major benefit: GHC should suck in many fewer interface files when
compiling (esp with -O).  (You can see this with -ddump-rn-stats.)

It's also some 1500 lines of code shorter than before.

**	So expect bugs!  I can do a 3-stage bootstrap, and run
**	the test suite, but you may be doing stuff I havn't tested.
** 	Don't update if you are relying on a working HEAD.


In particular, (a) External Core and (b) GHCi are very little tested.

	But please, please DO test this version!


	------------------------
		Big things
	------------------------

Interface files, version control, and importing declarations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* There is a totally new data type for stuff that lives in interface files:
	Original names			IfaceType.IfaceExtName
	Types				IfaceType.IfaceType
	Declarations (type,class,id)	IfaceSyn.IfaceDecl
	Unfoldings			IfaceSyn.IfaceExpr
  (Previously we used HsSyn for type/class decls, and UfExpr for unfoldings.)
  The new data types are in iface/IfaceType and iface/IfaceSyn.  They are
  all instances of Binary, so they can be written into interface files.
  Previous engronkulation concering the binary instance of RdrName has
  gone away -- RdrName is not an instance of Binary any more.  Nor does
  Binary.lhs need to know about the ``current module'' which it used to,
  which made it specialised to GHC.

  A good feature of this is that the type checker for source code doesn't
  need to worry about the possibility that we might be typechecking interface
  file stuff.  Nor does it need to do renaming; we can typecheck direct from
  IfaceSyn, saving a whole pass (module TcIface)

* Stuff from interface files is sucked in *lazily*, rather than being eagerly
  sucked in by the renamer. Instead, we use unsafeInterleaveIO to capture
  a thunk for the unfolding of an imported function (say).  If that unfolding
  is every pulled on, TcIface will scramble over the unfolding, which may
  in turn pull in the interface files of things mentioned in the unfolding.

  The External Package State is held in a mutable variable so that it
  can be side-effected by this lazy-sucking-in process (which may happen
  way later, e.g. when the simplifier runs).   In effect, the EPS is a kind
  of lazy memo table, filled in as we suck things in.  Or you could think
  of it as a global symbol table, populated on demand.

* This lazy sucking is very cool, but it can lead to truly awful bugs. The
  intent is that updates to the symbol table happen atomically, but very bad
  things happen if you read the variable for the table, and then force a
  thunk which updates the table.  Updates can get lost that way. I regret
  this subtlety.

  One example of the way it showed up is that the top level of TidyPgm
  (which updates the global name cache) to be much more disciplined about
  those updates, since TidyPgm may itself force thunks which allocate new
  names.

* Version numbering in interface files has changed completely, fixing
  one major bug with ghc --make.  Previously, the version of A.f changed
  only if A.f's type and unfolding was textually different.  That missed
  changes to things that A.f's unfolding mentions; which was fixed by
  eagerly sucking in all of those things, and listing them in the module's
  usage list.  But that didn't work with --make, because they might have
  been already sucked in.

  Now, A.f's version changes if anything reachable from A.f (via interface
  files) changes.  A module with unchanged source code needs recompiling
  only if the versions of any of its free variables changes. [This isn't
  quite right for dictionary functions and rules, which aren't mentioned
  explicitly in the source.  There are extensive comments in module MkIface,
  where all version-handling stuff is done.]

* We don't need equality on HsDecls any more (because they aren't used in
  interface files).  Instead we have a specialised equality for IfaceSyn
  (eqIfDecl etc), which uses IfaceEq instead of Bool as its result type.
  See notes in IfaceSyn.

* The horrid bit of the renamer that tried to predict what instance decls
  would be needed has gone entirely.  Instead, the type checker simply
  sucks in whatever instance decls it needs, when it needs them.  Easy!

  Similarly, no need for 'implicitModuleFVs' and 'implicitTemplateHaskellFVs'
  etc.  Hooray!


Types and type checking
~~~~~~~~~~~~~~~~~~~~~~~
* Kind-checking of types is far far tidier (new module TcHsTypes replaces
  the badly-named TcMonoType).  Strangely, this was one of my
  original goals, because the kind check for types is the Right Place to
  do type splicing, but it just didn't fit there before.

* There's a new representation for newtypes in TypeRep.lhs.  Previously
  they were represented using "SourceTypes" which was a funny compromise.
  Now they have their own constructor in the Type datatype.  SourceType
  has turned back into PredType, which is what it used to be.

* Instance decl overlap checking done lazily.  Consider
	instance C Int b
	instance C a Int
  These were rejected before as overlapping, because when seeking
  (C Int Int) one couldn't tell which to use.  But there's no problem when
  seeking (C Bool Int); it can only be the second.

  So instead of checking for overlap when adding a new instance declaration,
  we check for overlap when looking up an Inst.  If we find more than one
  matching instance, we see if any of the candidates dominates the others
  (in the sense of being a substitution instance of all the others);
  and only if not do we report an error.



	------------------------
	     Medium things
	------------------------

* The TcRn monad is generalised a bit further.  It's now based on utils/IOEnv.lhs,
  the IO monad with an environment.  The desugarer uses the monad too,
  so that anything it needs can get faulted in nicely.

* Reduce the number of wired-in things; in particular Word and Integer
  are no longer wired in.  The latter required HsLit.HsInteger to get a
  Type argument.  The 'derivable type classes' data types (:+:, :*: etc)
  are not wired in any more either (see stuff about derivable type classes
  below).

* The PersistentComilerState is now held in a mutable variable
  in the HscEnv.  Previously (a) it was passed to and then returned by
  many top-level functions, which was painful; (b) it was invariably
  accompanied by the HscEnv.  This change tidies up top-level plumbing
  without changing anything important.

* Derivable type classes are treated much more like 'deriving' clauses.
  Previously, the Ids for the to/from functions lived inside the TyCon,
  but now the TyCon simply records their existence (with a simple boolean).
  Anyone who wants to use them must look them up in the environment.

  This in turn makes it easy to generate the to/from functions (done
  in types/Generics) using HsSyn (like TcGenDeriv for ordinary derivings)
  instead of CoreSyn, which in turn means that (a) we don't have to figure
  out all the type arguments etc; and (b) it'll be type-checked for us.
  Generally, the task of generating the code has become easier, which is
  good for Manuel, who wants to make it more sophisticated.

* A Name now says what its "parent" is. For example, the parent of a data
  constructor is its type constructor; the parent of a class op is its
  class.  This relationship corresponds exactly to the Avail data type;
  there may be other places we can exploit it.  (I made the change so that
  version comparison in interface files would be a bit easier; but in
  fact it tided up other things here and there (see calls to
  Name.nameParent).  For example, the declaration pool, of declararations
  read from interface files, but not yet used, is now keyed only by the 'main'
  name of the declaration, not the subordinate names.

* New types OccEnv and OccSet, with the usual operations.
  OccNames can be efficiently compared, because they have uniques, thanks
  to the hashing implementation of FastStrings.

* The GlobalRdrEnv is now keyed by OccName rather than RdrName.  Not only
  does this halve the size of the env (because we don't need both qualified
  and unqualified versions in the env), but it's also more efficient because
  we can use a UniqFM instead of a FiniteMap.

  Consequential changes to Provenance, which has moved to RdrName.

* External Core remains a bit of a hack, as it was before, done with a mixture
  of HsDecls (so that recursiveness and argument variance is still inferred),
  and IfaceExprs (for value declarations).  It's not thoroughly tested.


	------------------------
	     Minor things
	------------------------

* DataCon fields dcWorkId, dcWrapId combined into a single field
  dcIds, that is explicit about whether the data con is a newtype or not.
  MkId.mkDataConWorkId and mkDataConWrapId are similarly combined into
  MkId.mkDataConIds

* Choosing the boxing strategy is done for *source* type decls only, and
  hence is now in TcTyDecls, not DataCon.

* WiredIn names are distinguished by their n_sort field, not by their location,
  which was rather strange

* Define Maybes.mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
  and use it here and there

* Much better pretty-printing of interface files (--show-iface)

Many, many other small things.


	------------------------
	     File changes
	------------------------
* New iface/ subdirectory
* Much of RnEnv has moved to iface/IfaceEnv
* MkIface and BinIface have moved from main/ to iface/
* types/Variance has been absorbed into typecheck/TcTyDecls
* RnHiFiles and RnIfaces have vanished entirely.  Their
  work is done by iface/LoadIface
* hsSyn/HsCore has gone, replaced by iface/IfaceSyn
* typecheck/TcIfaceSig has gone, replaced by iface/TcIface
* typecheck/TcMonoType has been renamed to typecheck/TcHsType
* basicTypes/Var.hi-boot and basicTypes/Generics.hi-boot have gone altogether

Legacy Removal
~~~~~~~~~~~~~~

The following features have been consigned to the bit bucket:

  _ccall_
  _casm_
  ``....''  (lit-lits)
  the CCallable class
  the CReturnable class

Disable update-in-place.  In its current form, it has a serious bug:
if the thunk being updated happens to have turned into a BLACKHOLE_BQ,
then the mutable list will be corrupted by the update.

Disabling update-in-place has some performance implications: many
programs are not affected, but one program in nofib (nucleic2) goes
about 20% slower.  However, I can get it to go 300% faster by adding a
few strictness annotations and compiling with -funbox-strict-fields.

Another cost-centre-restoring fix.  Restoring the cost centre in an
unboxed-tuple case alternative was using the wrong stack offset.

When restoring the cost centre in a let-no-escape, don't free the
stack slot containing it.  We might need the saved cost centre again
for a recursive call to this let-no-escape.

Should fix profiling a bit more.

Restoring of cost centre in let-no-escape: we need to do this after
binding the args to stack locations, otherwise we end up grabbing the
wrong slot.

Should hopefully fix profiling crashes.  We still don't pay any
attention to the cost centre attached to the let-no-escape binding
itself, which looks wrong, but I don't intend to do anything about
that right now.

When doing update-in-place, there is a (small) chance that the thunk
may have been blackholed and another thread might be waiting on it.
We can't therefore just splat it with the value; we have to check
whether it is a blocking queue and awaken any threads that might be
waiting on it if so.

Should fix the scavenge_mutable_list crash reported recently.  If it
does, it will be merged to STABLE.

--------------------------
	Fix two External-Core bugs
	--------------------------

1.  An inadvertent "let x = ...x..." bug in TcRnDriver

2.  Adjust the new -main-is story, so that the root module is called
	":Main" instead of "$Main".
    This means that the z-encoded module name is "ZCMain" rather than "zdMain",
    which in keeps the External-Core lexer happy.  And is more consistent generally.

3.  Make the renamer happy to see definitions from modules other than the "home" one,
    when doing External Core.  In the main module, there'll be a definition for
    ZCMain.main.

import fix

Fixes two minor bugs that I came across in the old
CgCase code generation:

1. We were generating
	tmp = Sp[1]
	... more uses of Sp[1]....
instead of
	tmp = Sp[1]
	... more uses of tmp....
in the (case v of ...prim alts...) situation

2. The cost-centre restoration wasn't right for let-no-escapes

I kept this fix separate, becuase it does change the code generated
slightly.

------------------------
       Tidy up the code generator
	------------------------

The code generation for 'case' expressions had grown
huge and gnarly.  This commit removes about 120 lines of
code, and makes it a lot easier to read too. I think the code
generated is identical.

Part of this was to simplify the StgCase data type, so
that it is more like the Core case: there is a simple list
of alternatives, and the DEFAULT (if present) must be the
first.  This tidies and simplifies other Stg passes.

Fix previous -main-is commit

-------------------
	Dealing with 'main'
	-------------------

1.  In GHC 6.0, a module with no "module Main ... where" header
    elicited an error "main is not in scope" if 'main' is not defined.  We
    don't want this behaviour in GHCi.  This happened because the parser
    expanded the (absent) header to "module Main( main ) where", and the
    'main' in the export list isn't.

Solution: elaborate HsModule to record whether the 'module ..." header was
given explicitly by the user or not.


2.  Add a -main-is flag, and document it, so that you can have a 'main' function
that is not Main.main.  Summary of changes

* The -main-is flag nominates what the main function is to be (see the documentation).
	No -main-is flag 	says that the main function is Main.main
	-main-is Foo.baz	says that the main function is Foo.baz
	-main-is Foo		says that the main function is Foo.main
	-main-is baz		says that the main function is Main.baz

  Let's say  you say -main-is Foo.baz

* TcRnDriver injects the extra definition
	$Mian.main :: IO t
	$Main.main = baz
  in the module Foo.   Note the naming, which is a bit different than before;
  previously the extra defn was for Main.$main.  The RTS invokes zdMain_main_closure.

* CodeGen injects an extra initialisation block into module Foo, thus
	stginit_zdMain {
		stginit_Foo
	}
  That ensures that the RTS can initialise stginit_zdMain.

Update IA64 port to work with gcc 3.3.

Prune imports

Eeek!  intsToReverseBitmap was borked for bitmaps with more than
wORD_SIZE_IN_BITS entries.

Change the way SRTs are represented:

Previously, the SRT associated with a function or thunk would be a
sub-list of the enclosing top-level function's SRT.  But this approach
can lead to lots of duplication: if a CAF is referenced in several
different thunks, then it may appear several times in the SRT.
Let-no-escapes compound the problem, because the occurrence of a
let-no-escape-bound variable would expand to all the CAFs referred to
by the let-no-escape.

The new way is to describe the SRT associated with a function or thunk
as a (pointer+offset,bitmap) pair, where the pointer+offset points
into some SRT table (the enclosing function's SRT), and the bitmap
indicates which entries in this table are "live" for this closure.
The bitmap is stored in the 16 bits previously used for the length
field, but this rarely overflows.  When it does overflow, we store the
bitmap externally in a new "SRT descriptor".

Now the enclosing SRT can be a set, hence eliminating the duplicates.

Also, we now have one SRT per top-level function in a recursive group,
where previously we used to have one SRT for the whole group.  This
helps keep the size of SRTs down.

Bottom line: very little difference most of the time.  GHC itself got
slightly smaller.  One bad case of a module in GHC which had a huge
SRT has gone away.

While I was in the area:

  - Several parts of the back-end require bitmaps.  Functions for
    creating bitmaps are now centralised in the Bitmap module.

  - We were trying to be independent of word-size in a couple of
    places in the back end, but we've now abandoned that strategy so I
    simplified things a bit.

A round of space-leak fixing.

  - re-instate zapping of the PersistentCompilerState at various
    points during the compilation cycle in HscMain.  This affects
    one-shot compilation only, since in this mode the information
    collected in the PCS is not required after creating the final
    interface file.

  - Unravel the recursive dependency between MkIface and
    CoreTidy/CoreToStg.  Previously the CafInfo for each binding was
    calculated by CoreToStg, and fed back into the IdInfo of the Ids
    generated by CoreTidy (an earlier pass).  MkIface then took this
    IdInfo and the bindings from CoreTidy to generate the interface;
    but it couldn't do this until *after* CoreToStg, because the CafInfo
    hadn't been calculated yet.  The result was that the CoreTidy
    output lived until after CoreToStg, and at the same time as the
    CorePrep and STG syntax, which is wasted space, not to mention
    the complexity and general ugliness in HscMain.

    So now we calculate CafInfo directly in CoreTidy.  The downside is
    that we have to predict what CorePrep is going to do to the
    bindings so we can tell what will turn into a CAF later, but it's
    no worse than before (it turned out that we were doing this
    prediction before in CoreToStg anyhow).

  - The typechecker lazilly typechecks unfoldings.  It turns out that
    this is a good idea from a performance perspective, but it also
    means that it must hang on to all the information it needs to
    do the typechecking.  Previously this meant holding on to the
    whole of the typechecker's environment, which includes all sorts
    of stuff which isn't necessary to typecheck unfoldings.  By paring
    down the environment captured by the lazy unfoldings, we can
    save quite a bit of space in the phases after typechecking.

-------------------------------------
  Big upheaval to the way that constructors are named
	-------------------------------------

This commit enshrines the new story for constructor names.  We could never
really get External Core to work nicely before, but now it does.

The story is laid out in detail in the Commentary
	ghc/docs/comm/the-beast/data-types.html
so I will not repeat it here.

	[Manuel: the commentary isn't being updated, apparently.]

However, the net effect is that in Core and in External Core, contructors look
like constructors, and the way things are printed is all consistent.

It is a fairly pervasive change (which is why it has been so long postponed),
but I hope the question is now finally closed.

All the libraries compile etc, and I've run many tests, but doubtless there will
be some dark corners.

Update comments

Simplify the bitmap-generating code by collecting all the pointer
words rather than all the non-pointer words, and then subtracting
these from a bitmap made of all ones.  This is simpler because we only
have to look in the bindings, rather than combining information from
bindings and the free stack slot list.

Expand bitmaps to cover the full size of the stack frame.  Previously
the bitmap would stop at the last non-zero bit, which might shorten
the bitmap by one or more words.  The behaviour used to be correct,
but with the eval/apply changes bitmaps must now cover the entire
stack frame rather than everything up to the last non-pointer word.

Comment fix.

Make the new info-table construction code word without instance Bits
Int (i.e. GHC 4.08.x).  This probably makes it more correct, too.

Tidy up info table generation

Merge the eval-apply-branch on to the HEAD
------------------------------------------

This is a change to GHC's evaluation model in order to ultimately make
GHC more portable and to reduce complexity in some areas.

At some point we'll update the commentary to describe the new state of
the RTS.  Pending that, the highlights of this change are:

  - No more Su.  The Su register is gone, update frames are one
    word smaller.

  - Slow-entry points and arg checks are gone.  Unknown function calls
    are handled by automatically-generated RTS entry points (AutoApply.hc,
    generated by the program in utils/genapply).

  - The stack layout is stricter: there are no "pending arguments" on
    the stack any more, the stack is always strictly a sequence of
    stack frames.

    This means that there's no need for LOOKS_LIKE_GHC_INFO() or
    LOOKS_LIKE_STATIC_CLOSURE() any more, and GHC doesn't need to know
    how to find the boundary between the text and data segments (BIG WIN!).

  - A couple of nasty hacks in the mangler caused by the neet to
    identify closure ptrs vs. info tables have gone away.

  - Info tables are a bit more complicated.  See InfoTables.h for the
    details.

  - As a side effect, GHCi can now deal with polymorphic seq.  Some bugs
    in GHCi which affected primitives and unboxed tuples are now
    fixed.

  - Binary sizes are reduced by about 7% on x86.  Performance is roughly
    similar, some programs get faster while some get slower.  I've seen
    GHCi perform worse on some examples, but haven't investigated
    further yet (GHCi performance *should* be about the same or better
    in theory).

  - Internally the code generator is rather better organised.  I've moved
    info-table generation from the NCG into the main codeGen where it is
    shared with the C back-end; info tables are now emitted as arrays
    of words in both back-ends.  The NCG is one step closer to being able
    to support profiling.

This has all been fairly thoroughly tested, but no doubt I've messed
up the commit in some way.

Behave decently if there are NoStubs in ForeignStubs

Import wibbles

--------------------------------------
	Make Template Haskell into the HEAD
	--------------------------------------

This massive commit transfers to the HEAD all the stuff that
Simon and Tim have been doing on Template Haskell.  The
meta-haskell-branch is no more!

WARNING: make sure that you

  * Update your links if you are using link trees.
    Some modules have been added, some have gone away.

  * Do 'make clean' in all library trees.
    The interface file format has changed, and you can
    get strange panics (sadly) if GHC tries to read old interface files:
    e.g.  ghc-5.05: panic! (the `impossible' happened, GHC version 5.05):
	  Binary.get(TyClDecl): ForeignType

  * You need to recompile the rts too; Linker.c has changed


However the libraries are almost unaltered; just a tiny change in
Base, and to the exports in Prelude.


NOTE: so far as TH itself is concerned, expression splices work
fine, but declaration splices are not complete.


		---------------
		The main change
		---------------

The main structural change: renaming and typechecking have to be
interleaved, because we can't rename stuff after a declaration splice
until after we've typechecked the stuff before (and the splice
itself).

* Combine the renamer and typecheker monads into one
	(TcRnMonad, TcRnTypes)
  These two replace TcMonad and RnMonad

* Give them a single 'driver' (TcRnDriver).  This driver
  replaces TcModule.lhs and Rename.lhs

* The haskell-src library package has a module
	Language/Haskell/THSyntax
  which defines the Haskell data type seen by the TH programmer.

* New modules:
	hsSyn/Convert.hs 	converts THSyntax -> HsSyn
	deSugar/DsMeta.hs 	converts HsSyn -> THSyntax

* New module typecheck/TcSplice type-checks Template Haskell splices.

		-------------
		Linking stuff
		-------------

* ByteCodeLink has been split into
	ByteCodeLink	(which links)
	ByteCodeAsm	(which assembles)

* New module ghci/ObjLink is the object-code linker.

* compMan/CmLink is removed entirely (was out of place)
  Ditto CmTypes (which was tiny)

* Linker.c initialises the linker when it is first used (no need to call
  initLinker any more).  Template Haskell makes it harder to know when
  and whether to initialise the linker.


	-------------------------------------
	Gathering the LIE in the type checker
	-------------------------------------

* Instead of explicitly gathering constraints in the LIE
	tcExpr :: RenamedExpr -> TcM (TypecheckedExpr, LIE)
  we now dump the constraints into a mutable varabiable carried
  by the monad, so we get
	tcExpr :: RenamedExpr -> TcM TypecheckedExpr

  Much less clutter in the code, and more efficient too.
  (Originally suggested by Mark Shields.)


		-----------------
		Remove "SysNames"
		-----------------

Because the renamer and the type checker were entirely separate,
we had to carry some rather tiresome implicit binders (or "SysNames")
along inside some of the HsDecl data structures.  They were both
tiresome and fragile.

Now that the typechecker and renamer are more intimately coupled,
we can eliminate SysNames (well, mostly... default methods still
carry something similar).

		-------------
		Clean up HsPat
		-------------

One big clean up is this: instead of having two HsPat types (InPat and
OutPat), they are now combined into one.  This is more consistent with
the way that HsExpr etc is handled; there are some 'Out' constructors
for the type checker output.

So:
	HsPat.InPat	--> HsPat.Pat
	HsPat.OutPat	--> HsPat.Pat
	No 'pat' type parameter in HsExpr, HsBinds, etc

	Constructor patterns are nicer now: they use
		HsPat.HsConDetails
	for the three cases of constructor patterns:
		prefix, infix, and record-bindings

	The *same* data type HsConDetails is used in the type
	declaration of the data type (HsDecls.TyData)

Lots of associated clean-up operations here and there.  Less code.
Everything is wonderful.

Remove bogus warning

Recent changes to simplify PrimRep had introduced a bug: the heap
check code was assuming that anything with PtrRep representation was
enterable.  This isn't the case for the unpointed primitive types
(eg. ByteArray#), resulting in the ARR_WORDS crash in last night's
build.

This bug isn't in STABLE.

Housekeeping:

  - The main goal is to remove dependencies on hslibs for a
    bootstrapped compiler, leaving only a requirement that the
    packages base, haskell98 and readline are built in stage 1 in
    order to bootstrap.  We're almost there: Posix is still required
    for signal handling, but all other dependencies on hslibs are now
    gone.

    Uses of Addr and ByteArray/MutableByteArray array are all gone
    from the compiler.  PrimPacked defines the Ptr type for GHC 4.08
    (which didn't have it), and it defines simple BA and MBA types to
    replace uses of ByteArray and MutableByteArray respectively.

  - Clean up import lists.  HsVersions.h now defines macros for some
    modules which have moved between GHC versions.  eg. one now
    imports 'GLAEXTS' to get at unboxed types and primops in the
    compiler.

    Many import lists have been sorted as per the recommendations in
    the new style guidelines in the commentary.

I've built the compiler with GHC 4.08.2, 5.00.2, 5.02.3, 5.04 and
itself, and everything still works here.  Doubtless I've got something
wrong, though.