Iterators
---------
	* `yield' is no longer a keyword, it only has special
	  meaning before a return or break keywords.

	* Study side effects with assign
	* Study TemporaryStorage/LocalStorage -> Merge/rename

	* Reset should throw not implemented now.

Instance idea
-------------

	It would be nice to have things that can be "instances" to have an
	EmitInstance method (this would default to nothing).

	The idea is to be able to use efficiently the instance data on stack
	manipulations, as opposed to the current scheme, where we basically have
	a few special cases.

Optimization ideas
------------------

	Currently when we build a type cache, it contains private members,
	internal members, and internal protected members;   We should trim
	these out, as it shows up on the profile.

	We create too many Arraylists;  When we know the size, we should create
	an array;

	During parsing we use arraylists to accumulate data, like this:

		thing:
		
		thing_list
			: thing { $$ =new ArrayList (); $$.Add ($1); }
			| thing_list thing { ArrayList a = $1; a.Add ($2); $$ = a; }

	We probably could start using "Pairs" there:

		thing_list
			: thing { $$ = new Pair ($1, null); }
			| thing_list thing { Pair p = $1; $$ = new Pair ($2, $1); }


Anonymous Methods
-----------------

	Plan:

		* Resolve anonymous methods before.
		* Each time a Local matches, if the mode is `InAnonymous', flag
	  	  the VariableInfo for `proxying'.
		* During Resolve track the depth required for local variables.
		* Before Emit, create proxy classes with proper depth.
		* Emit.

Open question:
		Create a toplevel block for anonymous methods?	

EmitContext.ResolveTypeTree
---------------------------

	We should investigate its usage.  The problem is that by default
	this will be set when calling FindType, that triggers a more expensive
	lookup.

	I believe we should pass the current EmitContext (which has this turned off
	by default) to ResolveType/REsolveTypeExpr and then have the routines that
	need ResolveType to pass null as the emit context.

DeclareLocal audit
------------------

	DeclareLocal is used in various statements.  The audit should be done
	in two steps:

		* Identify all the declare locals.

		* Identify its uses.

		* Find if we can make wrapper functions for all of them.

	Then we can move DeclareLocal into a helper class.

	This is required to fix foreach in iterators.

Large project:
--------------

	Drop FindMembers as our API and instead extract all the data
	out of a type the first time into our own datastructures, and
	use that to navigate and search the type instead of the
	callback based FindMembers.	

	Martin has some some of this work with his TypeHandle code
	that we could use for this.

Notes on memory allocation
--------------------------

	Outdated:

	A run of the AllocationProfile shows that the compiler allocates roughly
	30 megabytes of strings.  From those, 20 megabytes come from
	LookupType.  

	See the notes on current_container problems below on memory usage.  

LookupTypeReflection:
---------------------

	With something like `System.Object', LookupTypeReflection will be called
	twice: once to find out that `System' is not a type and once
	for System.Object.

	This is required because System.Reflection requires that the type/nested types are
	not separated by a dot but by a plus sign.

	A nested class would be My+Class (My being the toplevel, Class the nested one).

	It is interesting to look at the most called lookups when bootstrapping MCS:

    647	LTR: ArrayList
    713	LTR: System.Globalization
    822	LTR: System.Object+Expression
    904	LTR: Mono.CSharp.ArrayList
    976	LTR: System.Runtime.CompilerServices
    999	LTR: Type
   1118	LTR: System.Runtime
   1208	LTR: Mono.CSharp.Type
   1373	LTR: Mono.Languages
   1599	LTR: System.Diagnostics
   2036	LTR: System.Text
   2302	LTR: System.Reflection.Emit
   2515	LTR: System.Collections
   4527	LTR: System.Reflection
  22273	LTR: Mono.CSharp
  24245	LTR: System
  27005	LTR: Mono

	Analysis:
		The top 9 lookups are done for things which are not types.

		Mono.CSharp.Type happens to be a common lookup: the class Type
		used heavily in the compiler in the default namespace.

		RED FLAG:

		Then `Type' is looked up alone a lot of the time, this happens
		in parameter declarations and am not entirely sure that this is
		correct (FindType will pass to LookupInterfaceOrClass a the current_type.FullName,
		which for some reason is null!).  This seems to be a problem with a lost
		piece of context during FindType.

		System.Object is also used a lot as a toplevel class, and we assume it will
		have children, we should just shortcut this.

    A cache:

	Adding a cache and adding a catch for `System.Object' to flag that it wont be the
	root of a hierarchy reduced the MCS bootstrap time from 10.22 seconds to 8.90 seconds.

	This cache is currently enabled with SIMPLE_SPEEDUP in typemanager.cs.  Memory consumption
	went down from 74 megs to 65 megs with this change.  

Ideas:
------

	Instead of the hack that *knows* about System.Object not having any children classes,
	we should just make it simple for a probe to know that there is no need for it.

The use of DottedName
---------------------

	We could probably use a different system to represent names, like this:

	class Name {
		string simplename;
		Name parent;
	}

	So `System.ComponentModel' becomes:

		x: (System, null)
		y: (ComponentModel, x)

	The problem is that we would still need to construct the name to pass to
	GetType.

	This has been now implemented, its called "QualifiedIdentifier"

current_container/current_namespace and the DeclSpace
-----------------------------------------------------

	We are storing fully qualified names in the DeclSpace instead of the node,
	this is because `current_namespace' (Namepsace) is not a DeclSpace like
	`current_container'.

	The reason for storing the full names today is this:

	namespace X {
		class Y {
		}
	}

	namespace A {
		class Y {
		}
	}

	The problem is that we only use the namespace stack to track the "prefix"
	for typecontainers, but they are not typecontainers themselves, so we have
	to use fully qualified names, because both A.X and A.Y would be entered
	in the toplevel type container.  If we use the short names, there would be
	a name clash.

	To fix this problem, we have to make namespaces DeclSpaces.

	The full size, contrasted with the size that could be stored is:
		corlib:
			Size of strings held: 368901
			Size of strings short: 147863

		System:
			Size of strings held: 212677
			Size of strings short: 97521
		
		System.XML:
			Size of strings held: 128055
			Size of strings short: 35782
		
		System.Data:
			Size of strings held: 117896
			Size of strings short: 36153
		
		System.Web:
			Size of strings held: 194527
			Size of strings short: 58064
		
		System.Windows.Forms:
			Size of strings held: 220495
			Size of strings short: 64923

 	
TODO:

	1. Create a "partial" emit context for each TypeContainer..

	2. EmitContext should be partially constructed.  No IL Generator.

	interface_type review.

	parameter_array, line 952: `note: must be a single dimension array type'.  Validate this

Dead Code Elimination bugs:
---------------------------

	I should also resolve all the children expressions in Switch, Fixed, Using.

Major tasks:
------------

	Pinned and volatile require type modifiers that can not be encoded
	with Reflection.Emit.

	Properties and 17.6.3: Finish it.

	Implement base indexer access.

readonly variables and ref/out
	
BUGS
----

* Check for Final when overriding, if the parent is Final, then we cant
  allow an override.

* Interface indexers

	I have not figured out why the Microsoft version puts an
	`instance' attribute, and I am not generating this `instance' attribute.

	Explanation: The reason for the `instance' attribute on
	indexers is that indexers only apply to instances

* Break/Continue statements

	A finally block should reset the InLoop/LoopBegin/LoopEnd, as
	they are logically outside the scope of the loop.

* Break/continue part 2.

	They should transfer control to the finally block if inside a try/catch
	block.

* Method Registration and error CS111

	The way we use the method registration to signal 111 is wrong.
	
	Method registration should only be used to register methodbuilders,
	we need an alternate method of checking for duplicates.

*
> // CSC sets beforefieldinit
> class X {
>   // .cctor will be generated by compiler
>   public static readonly object O = new System.Object ();
>   public static void Main () {}
> }
> 

PENDING TASKS
-------------

* Merge test 89 and test-34

* Revisit

	Primary-expression, as it has now been split into 
	non-array-creation-expression and array-creation-expression.
		
* Code cleanup

	The information when registering a method in InternalParameters
	is duplicated, you can always get the types from the InternalParameters

* Emit modreq for volatiles

	Handle modreq from public apis.

* Emit `pinned' for pinned local variables.

	Both `modreq' and pinned will require special hacks in the compiler.

* Make sure that we are pinning the right variable

* Merge tree.cs, rootcontext.cs

OPTIMIZATIONS
-------------

* User Defined Conversions is doing way too many calls to do union sets that are not needed

* Add test case for destructors

* Places that use `Ldelema' are basically places where I will be
  initializing a value type.  I could apply an optimization to 
  disable the implicit local temporary from being created (by using
  the method in New).

* Dropping TypeContainer as an argument to EmitContext

 	My theory is that I can get rid of the TypeBuilder completely from
	the EmitContext, and have typecasts where it is used (from
	DeclSpace to where it matters).  

	The only pending problem is that the code that implements Aliases
	is on TypeContainer, and probably should go in DeclSpace.

* Use of local temporary in UnaryMutator

	We should get rid of the Localtemporary there for some cases

	This turns out to be very complex, at least for the post-version,
	because this case:

		a = i++

	To produce optimal code, it is necessary for UnaryMutator to know 
	that it is being assigned to a variable (the way the stack is laid
	out using dup requires the store to happen inside UnaryMutator).

* Tests

	Write tests for the various reference conversions.  We have
	test for all the numeric conversions.

* Optimizations

	In Indexers and Properties, probably support an EmitWithDup
	That emits the code to call Get and then leaves a this pointer
	in the stack, so that later a Store can be emitted using that
	this pointer (consider Property++ or Indexer++)

* Optimizations: variable allocation.

	When local variables of a type are required, we should request
	the variable and later release it when we are done, so that
	the same local variable slot can be reused later on.

* Add a cache for the various GetArrayMethod operations.

* MakeUnionSet Callers

	If the types are the same, there is no need to compute the unionset,
 	we can just use the list from one of the types.

* Factor the lookup code for class declarations an interfaces
  (interface.cs:GetInterfaceByName)

RECOMMENDATIONS
---------------

* Use of lexer.Location in the parser

	Currently we do:

	TOKEN nt TERMINAL nt TERMINAL nt3 {
		$$ = new Blah ($2, $4, $6, lexer.Location);
	}

	This is bad, because the lexer.Location is for the last item in `nt3'

	We need to change that to use this pattern:

	TOKEN { oob_stack.Push (lexer.Location) } nt TERMINAL nt TERMINAL nt3 {
		$$ = new Blah ($3, $5, $7, (Location) oob_stack.Pop ());
	}

	Notice how numbering of the arguments changes as the
	{ oob_stack.Push (lexer.Location) } takes a "slot"  in the productions.

* local_variable_declaration

	Not sure that this grammar is correct, we might have to
	resolve this during semantic analysis.

