ILSpy/NRefactory/ICSharpCode.NRefactory/CSharp/Parser/mcs/OTODO

---- This is a list of old tasks, just here for historical value ----

Open question:
		Create a toplevel block for anonymous methods?	

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.

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	Outdated: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.  

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

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

* Revisit

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

* local_variable_declaration

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

* 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++)

* 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).

* 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

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

	Implement base indexer access.

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

 	
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"

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

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.

	* `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