예제 #1
0
        public void TestConversionsWithCustomModifiers()
        {
            var text = @"
class C
{
    int[] a;
}
";

            var ilAssemblyReference = TestReferences.SymbolsTests.CustomModifiers.Modifiers.dll;

            var compilation = CreateCompilationWithMscorlib(text, new MetadataReference[] { ilAssemblyReference });
            compilation.VerifyDiagnostics(
                // (4,11): warning CS0169: The field 'C.a' is never used
                //     int[] a;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "a").WithArguments("C.a")
                );

            var classC = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");
            var typeIntArray = classC.GetMember<FieldSymbol>("a").Type;

            var interfaceI3 = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("I3");
            var typeIntArrayWithCustomModifiers = interfaceI3.GetMember<MethodSymbol>("M1").Parameters.Single().Type;

            Assert.True(typeIntArrayWithCustomModifiers.HasCustomModifiers(flagNonDefaultArraySizesOrLowerBounds: false));

            var conv = new BuckStopsHereBinder(compilation).Conversions;
            HashSet<DiagnosticInfo> useSiteDiagnostics = null;

            // no custom modifiers to custom modifiers
            Assert.Equal(ConversionKind.Identity, conv.ClassifyConversionFromType(typeIntArray, typeIntArrayWithCustomModifiers, ref useSiteDiagnostics).Kind);

            // custom modifiers to no custom modifiers
            Assert.Equal(ConversionKind.Identity, conv.ClassifyConversionFromType(typeIntArrayWithCustomModifiers, typeIntArray, ref useSiteDiagnostics).Kind);

            // custom modifiers to custom modifiers
            Assert.Equal(ConversionKind.Identity, conv.ClassifyConversionFromType(typeIntArrayWithCustomModifiers, typeIntArrayWithCustomModifiers, ref useSiteDiagnostics).Kind);
        }
예제 #2
0
        public void Test1()
        {
            var mscorlibRef = TestReferences.NetFx.v4_0_21006.mscorlib;
            var compilation = CSharpCompilation.Create("Test", references: new MetadataReference[] { mscorlibRef });
            var sys = compilation.GlobalNamespace.ChildNamespace("System");
            Conversions c = new BuckStopsHereBinder(compilation).Conversions;
            var types = new TypeSymbol[]
            {
            sys.ChildType("Object"),
            sys.ChildType("String"),
            sys.ChildType("Array"),
            sys.ChildType("Int64"),
            sys.ChildType("UInt64"),
            sys.ChildType("Int32"),
            sys.ChildType("UInt32"),
            sys.ChildType("Int16"),
            sys.ChildType("UInt16"),
            sys.ChildType("SByte"),
            sys.ChildType("Byte"),
            sys.ChildType("Double"),
            sys.ChildType("Single"),
            sys.ChildType("Decimal"),
            sys.ChildType("Char"),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Int64")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("UInt64")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Int32")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("UInt32")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Int16")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("UInt16")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("SByte")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Byte")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Double")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Single")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Decimal")),
            sys.ChildType("Nullable", 1).Construct(sys.ChildType("Char")),
            sys.ChildType("Exception"),
            sys.ChildNamespace("Collections").ChildType("IEnumerable"),
            sys.ChildNamespace("Collections").ChildNamespace("Generic").ChildType("IEnumerable", 1).Construct(sys.ChildType("Object")),
            sys.ChildNamespace("Collections").ChildNamespace("Generic").ChildType("IEnumerable", 1).Construct(sys.ChildType("String")),
            sys.ChildNamespace("Collections").ChildNamespace("Generic").ChildType("IEnumerable", 1).Construct(sys.ChildType("Char")),
            compilation.CreateArrayTypeSymbol(sys.ChildType("String")),
            compilation.CreateArrayTypeSymbol(sys.ChildType("Object")),
            sys.ChildNamespace("Collections").ChildNamespace("Generic").ChildType("IList", 1).Construct(sys.ChildType("String")),
            sys.ChildNamespace("Collections").ChildNamespace("Generic").ChildType("IList", 1).Construct(sys.ChildType("Object")),
            sys.ChildType("ArgumentException"),
            sys.ChildType("Delegate"),
            sys.ChildType("Func", 2).Construct(sys.ChildType("Exception"), sys.ChildType("Exception")),
            sys.ChildType("Func", 2).Construct(sys.ChildType("ArgumentException"), sys.ChildType("Object")),
            sys.ChildNamespace("Runtime").ChildNamespace("Serialization").ChildType("ISerializable"),
            sys.ChildType("IComparable", 0),
            };

            const ConversionKind Non = ConversionKind.NoConversion;
            const ConversionKind Idn = ConversionKind.Identity;
            const ConversionKind Inm = ConversionKind.ImplicitNumeric;
            const ConversionKind Inl = ConversionKind.ImplicitNullable;
            const ConversionKind Irf = ConversionKind.ImplicitReference;
            const ConversionKind Box = ConversionKind.Boxing;
            const ConversionKind Xrf = ConversionKind.ExplicitReference;
            const ConversionKind Ubx = ConversionKind.Unboxing;
            const ConversionKind Xnl = ConversionKind.ExplicitNullable;
            const ConversionKind Xnm = ConversionKind.ExplicitNumeric;

            ConversionKind[,] conversions =
            {
                // from   obj  str  arr  i64  u64  i32  u32  i16  u16  i08  u08  r64  r32  dec  chr ni64 nu64 ni32 nu32 ni16 nu16  ni8  nu8 nr64 nr32  ndc  nch  exc  ien  ieo  ies  iec  ars  aro  ils  ilo  aex  del  fee  fao  ser  cmp
                // to:    
                /*obj*/ { Idn, Irf, Irf, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Irf },
                /*str*/
                        { Xrf, Idn, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Non, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf },
                /*arr*/
                        { Xrf, Non, Idn, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Irf, Irf, Xrf, Xrf, Non, Non, Non, Non, Xrf, Xrf },
                /*i64*/
                        { Ubx, Non, Non, Idn, Xnm, Inm, Inm, Inm, Inm, Inm, Inm, Xnm, Xnm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*u64*/
                        { Ubx, Non, Non, Xnm, Idn, Xnm, Inm, Xnm, Inm, Xnm, Inm, Xnm, Xnm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*i32*/
                        { Ubx, Non, Non, Xnm, Xnm, Idn, Xnm, Inm, Inm, Inm, Inm, Xnm, Xnm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*u32*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Idn, Xnm, Inm, Xnm, Inm, Xnm, Xnm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*i16*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Xnm, Idn, Xnm, Inm, Inm, Xnm, Xnm, Xnm, Xnm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*u16*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Xnm, Xnm, Idn, Xnm, Inm, Xnm, Xnm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*i08*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Idn, Xnm, Xnm, Xnm, Xnm, Xnm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*u08*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Idn, Xnm, Xnm, Xnm, Xnm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*r64*/
                        { Ubx, Non, Non, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Idn, Inm, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*r32*/
                        { Ubx, Non, Non, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Xnm, Idn, Xnm, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*dec*/
                        { Ubx, Non, Non, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Inm, Xnm, Xnm, Idn, Inm, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*chr*/
                        { Ubx, Non, Non, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Xnm, Idn, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*ni64*/
                        { Ubx, Non, Non, Inl, Xnl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Xnl, Xnl, Inl, Idn, Xnl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Xnl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nu64*/
                        { Ubx, Non, Non, Xnl, Inl, Xnl, Inl, Xnl, Inl, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Xnl, Idn, Xnl, Inl, Xnl, Inl, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*ni32*/
                        { Ubx, Non, Non, Xnl, Xnl, Inl, Xnl, Inl, Inl, Inl, Inl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Idn, Xnl, Inl, Inl, Inl, Inl, Xnl, Xnl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nu32*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Inl, Xnl, Inl, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Xnl, Idn, Xnl, Inl, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*ni16*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Xnl, Inl, Xnl, Inl, Inl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Idn, Xnl, Inl, Inl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nu16*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Xnl, Xnl, Inl, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Xnl, Xnl, Xnl, Idn, Xnl, Inl, Xnl, Xnl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*ni8*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Idn, Xnl, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nu8*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Idn, Xnl, Xnl, Xnl, Xnl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nr64*/
                        { Ubx, Non, Non, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Idn, Inl, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nr32*/
                        { Ubx, Non, Non, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Inl, Xnl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Idn, Xnl, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*ndc*/
                        { Ubx, Non, Non, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Xnl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Inl, Xnl, Xnl, Idn, Inl, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*nch*/
                        { Ubx, Non, Non, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Inl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Xnl, Idn, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Ubx },
                /*exc*/
                        { Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Idn, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf, Irf, Non, Non, Non, Xrf, Xrf },
                /*ien*/
                        { Xrf, Irf, Irf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Idn, Irf, Irf, Irf, Irf, Irf, Irf, Irf, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*ieo*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Idn, Irf, Xrf, Irf, Irf, Irf, Irf, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*ies*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Idn, Xrf, Irf, Xrf, Irf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*iec*/
                        { Xrf, Irf, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Idn, Non, Non, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*ars*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Non, Idn, Xrf, Xrf, Xrf, Non, Non, Non, Non, Non, Non },
                /*aro*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Non, Irf, Idn, Xrf, Xrf, Non, Non, Non, Non, Non, Non },
                /*ils*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Xrf, Irf, Xrf, Idn, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*ilo*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Xrf, Irf, Irf, Xrf, Idn, Xrf, Xrf, Non, Non, Xrf, Xrf },
                /*aex*/
                        { Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf, Idn, Non, Non, Non, Xrf, Xrf },
                /*del*/
                        { Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf, Non, Idn, Irf, Irf, Xrf, Xrf },
                /*fee*/
                        { Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Idn, Xrf, Xrf, Non },
                /*fao*/
                        { Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Xrf, Irf, Idn, Xrf, Non },
                /*ser*/
                        { Xrf, Non, Xrf, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Non, Irf, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf, Irf, Irf, Irf, Irf, Idn, Xrf },
                /*cmp*/
                        { Xrf, Irf, Xrf, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Box, Xrf, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Xrf, Xrf, Xrf, Non, Non, Xrf, Idn },
            };

            HashSet<DiagnosticInfo> useSiteDiagnostics = null;

            for (int i = 0; i < types.Length; ++i)
            {
                for (int j = 0; j < types.Length; ++j)
                {
                    var kind = conversions[i, j];
                    var result = c.ClassifyConversionFromType(types[j], types[i], ref useSiteDiagnostics);
                    //Assert.Equal doesn't allow a string explanation, so provide one this way.
                    if (kind != result.Kind)
                    {
                        var result2 = c.ClassifyConversionFromType(types[j], types[i], ref useSiteDiagnostics); // set breakpoint here if this test is failing...
                        Assert.True(false, string.Format("Expected {0} but got {1} when converting {2} -> {3}", kind, result, types[j], types[i]));
                    }
                }
            }

            // UNDONE: Not tested yet:
            // UNDONE: Type parameter reference, boxing and unboxing conversions
            // UNDONE: User-defined conversions
            // UNDONE: Dynamic conversions
            // UNDONE: Enum conversions
            // UNDONE: Conversions involving expressions: null, lambda, method group
        }