Partial revert of mono#8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for
marshaling, otherwise it continues as in mono#8732 and uses
MONO_MARSHAL_CONV_OBJECT_STRUCT

Partial revert of mono#8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for
marshaling, otherwise it continues as in mono#8732 and uses
MONO_MARSHAL_CONV_OBJECT_STRUCT

Partial revert of mono#8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for
marshaling, otherwise it continues as in mono#8732 and uses
MONO_MARSHAL_CONV_OBJECT_STRUCT

Partial revert of mono/mono#8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for marshaling, otherwise it continues as in mono/mono#8732 and uses MONO_MARSHAL_CONV_OBJECT_STRUCT.

---

Also added tests for BSTR marshaling inside structs.  This actually works on mono master thanks to mono/mono#19701 but there was no test covering this case.

* [tests] Add BStr and VARIANT in structs interop tests

* [marshal] Fix reverse P/Invoke marshaling VARIANT fields

Partial revert of #8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for
marshaling, otherwise it continues as in #8732 and uses
MONO_MARSHAL_CONV_OBJECT_STRUCT

* [marshal] Marshal BSTR from reverse pinvokes

* [tests] Add BStr and VARIANT in structs interop tests

* [marshal] Fix reverse P/Invoke marshaling VARIANT fields

Partial revert of #8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for
marshaling, otherwise it continues as in #8732 and uses
MONO_MARSHAL_CONV_OBJECT_STRUCT

Partial revert of mono/mono#8732

If a managed struct is declared as

        public struct StructWithVariant
        {
            [MarshalAs (UnmanagedType.Struct)]
            public object data;
        };

Then the `data` field should be marshalled as a VARIANT.

The fix checks that the field's type is `object` and uses VARIANT for marshaling, otherwise it continues as in mono/mono#8732 and uses MONO_MARSHAL_CONV_OBJECT_STRUCT.

---

Also added tests for BSTR marshaling inside structs.  This actually works on mono master thanks to mono/mono#19701 but there was no test covering this case.

Co-authored-by: lambdageek <[email protected]>

…dType.Struct). (mono/mono#8732)

Fixes mono/mono#8250.

Commit migrated from mono/mono@2674424