EF6 and "NotSupportedException : Unknown LINQ expression of type 'Default'."

[BlaiseD]

EF6 doesn't like the default expression. Take the following configuration:

        [Fact]
        public void TestExpansion()
        {
            var mapper = new MapperConfiguration(cfg =>
            {
                cfg.CreateMap<TBuilding, CoreBuilding>()
                    .ForMember(d => d.Name, o => o.MapFrom(s => s.LongName));

                cfg.CreateMap<TBuilder, OpsBuilder>();

            }).CreateMapper();

            var modelQueryable = mapper.ProjectTo<CoreBuilding>(GetBuildings());
        }

        private static IQueryable<TBuilding> GetBuildings()
            => Array.Empty<TBuilding>().AsQueryable();

        public class TBuilding
        {
            public Int32 Id { get; set; }
            public String LongName { get; set; }
            public Int32 BuilderId { get; set; }
            public TBuilder Builder { get; set; }
        }

        public class TBuilder
        {
            public Int32 Id { get; set; }
            public String Name { get; set; }
        }

        public class CoreBuilding
        {
            public Guid Identity { get; set; }
            public string Name { get; set; }
            public OpsBuilder Builder { get; set; }
        }

        public class OpsBuilder
        {
            public Int32 Id { get; set; }
            public String Name { get; set; }
        }

In v13.0.1 modelQueryable.Expression is:

{AutoMapper.OData.EF6.Tests.ProjectionTest+TBuilding[].Select(dtoTBuilding => new CoreBuilding() {Builder = IIF((dtoTBuilding.Builder == default(Object)), default(OpsBuilder), new OpsBuilder() {Id = dtoTBuilding.Builder.Id, Name = dtoTBuilding.Builder.Name}), Name = dtoTBuilding.LongName})}

In v12.0.1:

{AutoMapper.OData.EF6.Tests.ProjectionTest+TBuilding[].Select(dtoTBuilding => new CoreBuilding() {Name = dtoTBuilding.LongName, Builder = IIF((dtoTBuilding.Builder == null), null, new OpsBuilder() {Id = dtoTBuilding.Builder.Id, Name = dtoTBuilding.Builder.Name})})}

For v13 EF6 throws:

  Message: 
System.NotSupportedException : Unknown LINQ expression of type 'Default'.

  Stack Trace: 
EntityExpressionVisitor.Visit(Expression exp)
<>c__DisplayClass22_0.<Nominate>b__0(Expression exp, Func`2 baseVisit)
BasicExpressionVisitor.Visit(Expression exp)
EntityExpressionVisitor.VisitBinary(BinaryExpression b)
EntityExpressionVisitor.VisitComparison(BinaryExpression expression)
EntityExpressionVisitor.Visit(Expression exp)
<>c__DisplayClass22_0.<Nominate>b__0(Expression exp, Func`2 baseVisit)

Do we care?

[lbargaoanu]

No, AM doesn't support EF6 anymore.

[github-actions[bot]]

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