[Mono-bugs] [Bug 377596] New: Cannot retrieve Generic Type Parameter Custom Attributes via Reflection

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https://bugzilla.novell.com/show_bug.cgi?id=377596


           Summary: Cannot retrieve Generic Type Parameter Custom Attributes
                    via Reflection
           Product: Mono: Runtime
           Version: SVN
          Platform: x86-64
        OS/Version: openSUSE 10.3
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: generics
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: jonpryor at vt.edu
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---


System.Type.GetCustomAttributes() should return custom attributes on generic
type parameters.

Sample program:

        // generic argument attributes?

        using System;
        using System.Reflection;

        [AttributeUsage (AttributeTargets.All)]
        public class DocAttribute : Attribute {
                public DocAttribute (string docs) {}
        }

        class Foo<[Doc ("T")] T, [Doc ("B")] B> 
                where T : class, new ()
                where B : Attribute
        {
                public T Bar { get{return null;}}
                public void M<[Doc ("X")] X> (X x)
                {
                }
        }

        class Test {
                public static void Main ()
                {
                        Type t = typeof(Foo<,>);
                        Type[] tArgs = t.GetGenericArguments ();
                        PrintGenericAttributes (tArgs);
                        MethodInfo m = t.GetMethod ("M");
                        PrintGenericAttributes (m.GetGenericArguments ());
                }

                static void PrintGenericAttributes (Type[] tArgs)
                {
                        foreach (Type ta in tArgs) {
                                Console.WriteLine ("Generic Parameter: {0}",
ta.Name);
                                Console.WriteLine ("\tGeneric Paramter
Attributes: {0}",
                                        ta.GenericParameterAttributes);
                                object[] ca = ta.GetCustomAttributes (true);
                                Console.WriteLine ("\tGetCustomAttributes={0};
count={1}", ca, ca.Length);
                                foreach (object o in ca)
                                        Console.WriteLine ("\tCustom Attribute:
{0}", o.GetType().FullName);
                                Type[] constraints =
ta.GetGenericParameterConstraints ();
                                foreach (Type tc in constraints)
                                        Console.WriteLine ("\tconstraint: {0}",
tc);
                        }
                }
        }

Expected output:

        Generic Parameter: T
                Generic Paramter Attributes: ReferenceTypeConstraint,
DefaultConstructorConstraint
                GetCustomAttributes=System.Object[]; count=1
                Custom Attribute: DocAttribute
        Generic Parameter: B
                Generic Paramter Attributes: None
                GetCustomAttributes=System.Object[]; count=2
                Custom Attribute: DocAttribute
                Custom Attribute: System.AttributeUsageAttribute
                constraint: System.Attribute
        Generic Parameter: X
                Generic Paramter Attributes: None
                GetCustomAttributes=System.Object[]; count=1
                Custom Attribute: DocAttribute

Notice in the output that GetCustomAttributes() returns a count >= 1 in all
cases.

Actual output under mono r98602:

        Generic Parameter: T
                Generic Paramter Attributes: ReferenceTypeConstraint,
DefaultConstructorConstraint
                GetCustomAttributes=System.Attribute[]; count=0
        Generic Parameter: B
                Generic Paramter Attributes: None
                GetCustomAttributes=System.Attribute[]; count=1
                Custom Attribute: System.AttributeUsageAttribute
                constraint: System.Attribute
        Generic Parameter: X
                Generic Paramter Attributes: None
                GetCustomAttributes=System.Attribute[]; count=0

Notice that the only parameter with count >= 1 is B, and that's for an
AttributeUsageAttribute.


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