Bug 4659 - Error in soft debugger method call thread
Summary: Error in soft debugger method call thread
Alias: None
Product: Runtime
Classification: Mono
Component: Debugger ()
Version: unspecified
Hardware: PC Linux
: High major
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2012-04-26 04:57 UTC by Marek Safar
Modified: 2012-05-03 07:54 UTC (History)
5 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Marek Safar 2012-04-26 04:57:08 UTC
Error in soft debugger method call thread on method String System.Nullable`1:ToString () on object System.Nullable`1[[System.DateTimeOffset, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]]
System.ArgumentException: Incorrect number or types of arguments
Parameter name: arguments
  at Mono.Debugger.Soft.ObjectMirror.EndInvokeMethodInternal (IAsyncResult asyncResult) [0x00071] in /home/marek/git/monodevelop/main/contrib/Mono.Debugger.Soft/Mono.Debugger.Soft/ObjectMirror.cs:262 
  at Mono.Debugger.Soft.StructMirror.EndInvokeMethod (IAsyncResult asyncResult) [0x00001] in /home/marek/git/monodevelop/main/contrib/Mono.Debugger.Soft/Mono.Debugger.Soft/StructMirror.cs:68 
  at Mono.Debugging.Soft.MethodCall.EndInvoke () [0x00074] in /home/marek/git/monodevelop/main/src/addins/MonoDevelop.Debugger.Soft/Mono.Debugging.Soft/SoftDebuggerAdaptor.cs:1275 

This happens for properties like

public DateTimeOffset? Date { get { ..... } }

which cannot be inspected at all
Comment 1 Jeffrey Stedfast 2012-05-02 16:33:36 UTC
Here's a sample appl:

using System;

namespace temp44
	class MainClass
		public static DateTime? Date { get; set; }

		public static void Main (string[] args)
			DateTime? date = null;

			return; // BREAK here and type "Date.ToString ()" in Immediate window

You'll notice that if you type "date.ToString ()" instead, it works fine. This seems to be because the runtime is returning null instead of a System.Nullable<DateTime> (set to null) when we request the Date property, and so... when we try to invoke System.Nullable<DateTime>.ToString() on a PrimitiveValue with a value of null, it fails with the argument exception.

The ctx.RuntimeInvoke() called in PropertyValueReference.cs:98 returns PrimitiveValue(null) when it should really be returning a StructMirror.

Inside VirtualMachine.DecodeValue (ValueImpl v), v.Type is VALUE_TYPE_ID_NULL so it ends up returning a PrimitiveValue instead of a StructMirror.
Comment 2 Zoltan Varga 2012-05-03 07:54:45 UTC
Fixed in master.