Generic parameters constrained with complex generic types fail to resolve.

[alexmg]

From [email protected] on April 03, 2013 22:44:08

What steps will reproduce the problem? Here is the situation with 2 failing tests :

    public interface IConstraint<T> { }

    public class Constrained<T1, T2>
        where T2 : IConstraint<T1>
    {
    }
    public interface IConstraintWithAddedArgument<T2, T1> : IConstraint<T1> { }

    [Test]
    public void CanResolveComponentWhenConstrainedArgumentIsGenericTypeWithMoreArgumentsThanGenericConstraint()
    {
        var builder = new ContainerBuilder();

        builder.RegisterGeneric(typeof(Constrained<,>));

        var container = builder.Build();

        Assert.That(container.IsRegistered<Constrained<int, IConstraintWithAddedArgument<string, int>>>());
    }


    public interface IConstrainedConstraint<T>
        where T : IEquatable<int> { }

    public interface IConstrainedConstraintWithAddedArgument<T1, T2> : IConstrainedConstraint<T2>
        where T2 : IEquatable<int>
    { }

    public interface IConstrainedConstraintWithOnlyAddedArgument<T1> : IConstrainedConstraintWithAddedArgument<T1, int>
    { }

    public class MultiConstrained<T1, T2>
      where T1 : IEquatable<int>
      where T2 : IConstrainedConstraint<T1>
    {
    }

    [Test]
    public void CanResolveComponentWhenConstraintsAreNested()
    {
        var builder = new ContainerBuilder();

        builder.RegisterGeneric(typeof(MultiConstrained<,>));

        var container = builder.Build();

        Assert.That(container.IsRegistered<MultiConstrained<int, IConstrainedConstraintWithOnlyAddedArgument<string>>>());
    } What is the expected output? What do you see instead? The requested services should be registred, but the following exceptions is thrown :

Autofac.Tests.Features. OpenGenerics .ComplexGenericsTests.CanResolveComponentWhenConstrainedArgumentIsGenericTypeWithMoreArgumentsThanGenericConstraint:
System.ArgumentException : The number of generic arguments provided doesn't equal the arity of the generic type definition.
Parameter name: instantiation

or

Autofac.Tests.Features. OpenGenerics .ComplexGenericsTests.CanResolveComponentWhenConstraintsAreNested:
System.ArgumentException : GenericArguments[0], 'System.String', on 'Autofac.Tests.Features. OpenGenerics .ComplexGenericsTests+IConstrainedConstraint1[T]' violates the constraint of type 'T'. ----> System.TypeLoadException : GenericArguments[0], 'System.String', on 'Autofac.Tests.Features. OpenGenerics .ComplexGenericsTests+IConstrainedConstraint1[T]' violates the constraint of type parameter 'T'.

The problem is in ParameterEqualsConstraint in TypeExtensions.cs. It's missing test cases.
Checking number of arguments and catching all others, all works correctly.

Attachment: ComplexGenericsTests.cs.patch TypeExtensions.cs.patch

Original issue: http://code.google.com/p/autofac/issues/detail?id=421

[alexmg]

From travis.illig on April 04, 2013 07:58:09

Thanks for reporting this and extra-super-thanks for including both a failing test and a patch! We'll take a look as soon as we can.

Labels: Module-Core

[alexmg]

From alex.meyergleaves on April 05, 2013 20:09:35

Owner: alex.meyergleaves

[alexmg]

From alex.meyergleaves on April 05, 2013 20:19:56

This issue was closed by revision 107b5d93cafe .

Status: Fixed

[alexmg]

From travis.illig on April 09, 2013 16:04:06

Issue 422 has been merged into this issue.