---- Reported by rodrigobamboo@gmail.com 2006-12-14 10:07:00 MST ----

using System.Collections.Generic;

class CantCastGenericListToArray
{
	public static void Main(string[] args)
	{
		IList<string> list = new string[] { "foo", "bar" };
		string[] array = (string[])list;
		if (list.Count != array.Length)
		{
			throw new System.ApplicationException();
		}
	}
}

Actual Results:
CantCastGenericListToArray.cs(8,34): error CS0030: Cannot convert type
`System.Collections.Generic.IList<string>' to `string[]'
Compilation failed: 1 error(s), 0 warnings

Expected Results:
Successful compilation.



---- Additional Comments From miguel@ximian.com 2006-12-18 19:17:40 MST ----

Per a discussion with Martin, these are just a few cases missing in
ExplicitReferenceConversionExists and ExplicitReferenceConversion in
mcs/convert.cs

The relevant piece of the spec that is missing is: 13.2.3 "Explicit
Reference Conversions" is missing the last two conversions that only
apply to the generics compiler.  These are:

"* From a one-dimensional array-type S[] to
System.Collections.Generic.IList<T> and its base
interfaces, provided there is an explicit reference conversion from S
to T.
* From System.Collections.Generic.IList<T> and its base interfaces to
a one-dimensional"
array-type S[], provided there is an implicit or explicit reference
conversion from S[] to
System.Collections.Generic.IList<T>. This is precisely when either S
and T are the same type
or there is an implicit or explicit reference conversion from S to T.



---- Additional Comments From miguel@ximian.com 2006-12-18 19:18:17 MST ----

The VM support is already in place, I ran the MS compiled programs on
Mono without any problem. 



---- Additional Comments From dmitchell@logos.com 2007-02-04 00:24:44 MST ----

Created an attachment
This patch will fix https://bugzilla.novell.com/show_bug.cgi?id=MONO80260




---- Additional Comments From dmitchell@logos.com 2007-02-04 00:29:18 MST ----

I've attached a patch that will fix the problem on the compiler end.

In testing the patch, I discovered that the runtime does not always behave like the 
Microsoft implementation. For example, the following program will compile under the 
Microsoft implementation, but the conversion will throw an exception:

using System.Collections.Generic;

class CantCastGenericListToArray
{
	public static void Main(string[] args)
	{
		IList<object> list = new object[] { "foo", "bar" };
		string[] array = (string[])list;
		if (list.Count != array.Length)
		{
			throw new System.ApplicationException();
		}
	}
}

However, no exceptions will be thrown in Mono. Does this qualify as a separate bug, or 
should this one be left open?



---- Additional Comments From miguel@ximian.com 2007-03-05 18:54:32 MST ----

Commited the patch, thanks!

Yes, we do need a separate bug for the runtime piece, I have it filed
as 81044.

Miguel

Imported an attachment (id=171098)

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