---- Reported by redforks@gmail.com 2006-11-19 02:49:31 MST ----

Pass an generic anonymous method to a constructor, like this:


delegate void TestFunc<T>(T val);

class A
{
	public A(TestFunc<int> func) { }
}

class TestClass
{
	readonly A a = new A(delegate(int a) { });
	static void Func<T>(TestFunc<T> func) { }
}


gmcs will crash:

Unhandled Exception: System.NullReferenceException: Object reference not
set to an instance of an object
  at Mono.CSharp.AnonymousMethod.DoCreateMethodHost
(Mono.CSharp.EmitContext ec) [0x00093] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/anonymous.cs:1363
  at Mono.CSharp.AnonymousContainer.Resolve (Mono.CSharp.EmitContext ec)
[0x0012a] in /tmp/scratch/BUILD/mono-1.2/mcs/mcs/anonymous.cs:1246
  at Mono.CSharp.AnonymousMethod.Resolve (Mono.CSharp.EmitContext ec)
[0x00000] in /tmp/scratch/BUILD/mono-1.2/mcs/mcs/anonymous.cs:1379
  at Mono.CSharp.AnonymousMethodExpression.Compatible
(Mono.CSharp.EmitContext ec, System.Type delegate_type) [0x00321] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/anonymous.cs:1111
  at Mono.CSharp.Convert.ImplicitConversionStandard
(Mono.CSharp.EmitContext ec, Mono.CSharp.Expression expr, System.Type
target_type, Location loc) [0x001b2] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/convert.cs:1342
  at Mono.CSharp.Convert.ImplicitConversion (Mono.CSharp.EmitContext ec,
Mono.CSharp.Expression expr, System.Type target_type, Location loc)
[0x00012] in /tmp/scratch/BUILD/mono-1.2/mcs/mcs/convert.cs:1233
  at Mono.CSharp.Invocation.VerifyArgumentsCompat (Mono.CSharp.EmitContext
ec, System.Collections.ArrayList Arguments, Int32 arg_count,
System.Reflection.MethodBase method, Boolean chose_params_expanded,
System.Type delegate_type, Boolean may_fail, Location loc) [0x000b1] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/expression.cs:4895
  at Mono.CSharp.Invocation.OverloadResolve (Mono.CSharp.EmitContext ec,
Mono.CSharp.MethodGroupExpr me, System.Collections.ArrayList Arguments,
Boolean may_fail, Location loc) [0x00609] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/expression.cs:4802
  at Mono.CSharp.New.DoResolve (Mono.CSharp.EmitContext ec) [0x0033c] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/expression.cs:5741
  at Mono.CSharp.Expression.Resolve (Mono.CSharp.EmitContext ec,
ResolveFlags flags) [0x00067] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/ecore.cs:415
  at Mono.CSharp.Expression.Resolve (Mono.CSharp.EmitContext ec) [0x00000]
in /tmp/scratch/BUILD/mono-1.2/mcs/mcs/ecore.cs:442
  at Mono.CSharp.FieldBase.ResolveInitializer () [0x00022] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/class.cs:5613
  at Mono.CSharp.ClassOrStruct.DefineFieldInitializers () [0x00025] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/class.cs:2793
  at Mono.CSharp.ClassOrStruct.Define () [0x00000] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/class.cs:2834
  at Mono.CSharp.RootContext.DefineTypes () [0x000e2] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/rootcontext.cs:585
  at Mono.CSharp.Driver.MainDriver (System.String[] args) [0x0053e] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/driver.cs:1675
  at Mono.CSharp.Driver.Main (System.String[] args) [0x0001f] in
/tmp/scratch/BUILD/mono-1.2/mcs/mcs/driver.cs:292

And I made a patch: 

Index: anonymous.cs
===================================================================
--- anonymous.cs        (revision 68052)
+++ anonymous.cs        (working copy)
@@ -1361,7 +1361,7 @@
                                member_name = new MemberName (name, args,
Location);

                                generic_method = new GenericMethod (
-                                       RootScope.NamespaceEntry,
RootScope, member_name,
+                                       RootScope != null ?
RootScope.NamespaceEntry : null, RootScope, member_name,
                                        new TypeExpression (ReturnType,
Location), Parameters);

                                generic_method.SetParameterInfo (null);



---- Additional Comments From redforks@gmail.com 2006-11-19 02:50:36 MST ----

Created an attachment (id=170916)
test csharp file




---- Additional Comments From redforks@gmail.com 2006-11-19 02:51:02 MST ----

Created an attachment (id=170917)
The patch




---- Additional Comments From rharinath@novell.com 2006-11-22 07:08:39 MST ----

Hmm, the posted patch would paper over the actual bug, and cause other
bugs elsewhere.  So, I'm not applying it to the tree.

Still, it's probably a useful workaround till we fix the bug -- in
case anyone else is bitten by the same bug.




---- Additional Comments From redforks@gmail.com 2006-11-22 22:53:38 MST ----

I don't understand:

RootScope.NamespaceEntry 
RootScope != null ? RootScope.NamespaceEntry : null

Are there acture difference? 

You don't fix the bug, is just ok. Because I found gmcs/mcs is not 
very usefull, I use csc instead, and try to run under mono and linux.
Two years, csc/gmcs can't build any of my csharp projects. I waited 
and waited, one bug fixed, many new bugs appeared. Maybe another 2 
years needed for mcs/gmcs usable, or maybe not.

Sorry my complain, I just can't wait any more.



---- Additional Comments From rharinath@novell.com 2006-11-23 09:24:39 MST ----

I'm talking about a development tree, not a release tree.  It's better
not to paper over bugs in the development tree, so that we can fix it
the right way.

In this particular case, 'RootScope' is null: either it shouldn't be,
or we shouldn't try to use its version of NamespaceEntry -- deciding
on either of these, and fixing the remaining code will require some
thought and some rewriting/refactoring.  (Passing a null
NamespaceEntry is not right, since, somewhere else, the code _will_
dereference that NamespaceEntry, and it will be harder to debug the
problem when it NullRefs there.)

In any case, surrounding and related code are being rewritten, and
we'll be in a better position to judge how to fix this bug once that
is done.



---- Additional Comments From martin@ximian.com 2006-11-24 09:56:48 MST ----

Just use `Host.NamespaceEntry' there - RootScope / Scope may be null,
but `Host' not. 



---- Additional Comments From rharinath@novell.com 2006-12-01 07:30:06 MST ----

This appears to have been fixed as part of Martin's recent rewrite.


Imported an attachment (id=170916)
Imported an attachment (id=170917)