[Mono-dev] Strange Casting bug in .net 4 profile

[Robert Jordan]

Hey,

I believe this is already fixed in trunk. It was a mismatch
between the 2.0 and 4.0 System.Configuration.dll that were
loaded together into the same appdomain. This means that
ServicesSection defined in these assemblies were actually
incompatible to each other.

Robert

On 18.08.2010 13:52, Gary Thomas wrote:
> Hi all,
> 	I have been using mono from trunk and playing with the WCF stuff when I noticed an InvalidCastException being thrown. I figured out that this only happened when using the .net 4 profile, when using .net 3.5 profile it didn't happen.
> I have put together a simple app to show the problem and here are the results.
>
> With .net 4:
>
> [mono] ~/Projects/CastBug @ dmcs CastBug.cs /reference:System.Configuration /reference:System.ServiceModel
> CastBug.cs(19,41): warning CS0219: The variable `ss' is assigned but its value is never used
> Compilation succeeded - 1 warning(s)
> [mono] ~/Projects/CastBug @ mono CastBug.exe
> System.ServiceModel.Configuration.ServicesSection
> section is ConfigurationSection True
> section is ServicesSection False
> ServiceSection type System.ServiceModel.Configuration.ServicesSection
> Casting section
>
> Unhandled Exception: System.InvalidCastException: Cannot cast from source type to destination type.
>    at CastBug.MainClass.Main (System.String[] args) [0x00000] in<filename unknown>:0
>
>
> With .net 3.5:
>
> [mono] ~/Projects/CastBug @ gmcs CastBug.cs /reference:System.Configuration /reference:System.ServiceModel
> CastBug.cs(19,41): warning CS0219: The variable `ss' is assigned but its value is never used
> Compilation succeeded - 1 warning(s)
> [mono] ~/Projects/CastBug @ mono CastBug.exe
> System.ServiceModel.Configuration.ServicesSection
> section is ConfigurationSection True
> section is ServicesSection True
> ServiceSection type System.ServiceModel.Configuration.ServicesSection
> Casting section
> Done casting section
>
> The runtime reports the type of the object as ServicesSection but casting it to a ServicesSection causes an InvalidCastException.
>
> Here is the test app:
>
> using System;
> using System.Configuration;
> using System.ServiceModel.Configuration;
>
> namespace CastBug
> {
>          class MainClass
>          {
>                  public static void Main (string[] args)
>                  {
>                          var section = ConfigurationManager.GetSection("system.serviceModel/services");
>                          Console.WriteLine(section.GetType().ToString());
>                          Console.WriteLine("section is ConfigurationSection {0}", section is ConfigurationSection);
>                          Console.WriteLine("section is ServicesSection {0}", section is ServicesSection);
>                          Console.WriteLine("ServiceSection type {0}", typeof(ServicesSection).ToString());
>
>                          Console.WriteLine("Casting section");
>                          // throws an InvalidCastException
>                          ServicesSection ss = (ServicesSection)section;
>                          Console.WriteLine("Done casting section");
>
>                  }
>          }
> }
>
> Is this a known issue? Should I report a bug? If it was a simple bug in the c# libraries I would have a go at fixing myself but this seem more fundamental than that.
>
> Thanks,
> Gary