[Mono-dev] strange behaviour with generics

[Marek Safar]

Hello,

Please fill a bug report at http://www.mono-project.com/Bugs with your 
separate class.

Thanks
Marek
> Hi,
>
> I am using version 1.2.5.1 <http://1.2.5.1> of Mono and I am having 
> some troubles in using a generic parameter in a method, which seems to 
> be a bug .
>
> The following code compiles fine:
>
>
> using  System;
>
> namespace  TestMethodParameterTypeMono
> {
>     class   Program
>    {
>       static   void  Main( string [] args)
>       {
>           Class1 < double > myClass1 = new   Class1 < double >();
>           int  i = myClass1.MethodB< DoubleCalculator >();
>       }
>    }
>
>     public   interface   ICalculator <T>
>    {
>       T Add(T a, T b);
>    }
>
>     public   struct   DoubleCalculator  : ICalculator < double >
>    {
>       public   double  Add( double  a, double  b)
>       {
>           return  a + b;
>       }
>    }
>
>     public   class   Class1 <T>
>       where  T : IComparable <T>
>    {
>       private   int  i = 5;
>       public   int  MethodB<C>() where  C : ICalculator <T>, new ()
>       {
>           return  i;
>       }
>    }
> }
>
>
> On the other hand, if I take the class Program and put it in a 
> different file and compile it isolated making a reference to the 
> previous generated .exe, the following compilation error appears:
>
> Program.cs(13,27): error CS0309: The type 
> `TestMethodParameterTypeMono.DoubleCalculator' must be convertible to 
> `TestMethodParameterTypeMono.ICalculator<TestMethodParameterTypeMono.DoubleCalculator>' 
> in order to use it as parameter `C' in the generic type or method 
> `TestMethodParameterTypeMono.Class1<double>.MethodB<C>()'
>
>
>
> Note that the constraint on type parameter C on MethodB is to 
> implement ICalculator<double>, which DoubleCalculator does, instead of 
> ICalculator<DoubleCalculator> as the message suggests.
>
> Am I missing something or is it really a bug? The separate class 
> Program compiles fine in Visual Studio 2005 making the reference.
>  
> Thanks,
> Felipe Portella
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