C# CSharp.BoundMethodGroup类代码示例

        public override Conversion GetMethodGroupConversion(BoundMethodGroup source, TypeSymbol destination, ref HashSet<DiagnosticInfo> useSiteDiagnostics)
        {
            // Must be a bona fide delegate type, not an expression tree type.
            if (!destination.IsDelegateType())
            {
                return Conversion.NoConversion;
            }

            var methodSymbol = GetDelegateInvokeMethodIfAvailable(destination);
            if ((object)methodSymbol == null)
            {
                return Conversion.NoConversion;
            }

            var resolution = ResolveDelegateMethodGroup(_binder, source, methodSymbol, ref useSiteDiagnostics);
            var conversion = (resolution.IsEmpty || resolution.HasAnyErrors) ?
                Conversion.NoConversion :
                ToConversion(resolution.OverloadResolutionResult, resolution.MethodGroup, (NamedTypeSymbol)destination);
            resolution.Free();
            return conversion;
        }

        public static bool ReportDelegateMethodGroupDiagnostics(Binder binder, BoundMethodGroup expr, TypeSymbol targetType, DiagnosticBag diagnostics)
        {
            var invokeMethodOpt = GetDelegateInvokeMethodIfAvailable(targetType);
            HashSet<DiagnosticInfo> useSiteDiagnostics = null;
            var resolution = ResolveDelegateMethodGroup(binder, expr, invokeMethodOpt, ref useSiteDiagnostics);
            diagnostics.Add(expr.Syntax, useSiteDiagnostics);

            bool hasErrors = resolution.HasAnyErrors;

            diagnostics.AddRange(resolution.Diagnostics);

            // SPEC VIOLATION: Unfortunately, we cannot exactly implement the specification for
            // the scenario in which an extension method that extends a value type is converted
            // to a delegate. The code we generate that captures a delegate to a static method
            // that is "partially evaluated" with the bound-to-the-delegate first argument
            // requires that the first argument be of reference type.
            //
            // SPEC VIOLATION: Similarly, we cannot capture a method of Nullable<T>, because
            // boxing a Nullable<T> gives a T, not a boxed Nullable<T>.
            //
            // We give special error messages in these situations.

            if (resolution.MethodGroup != null)
            {
                var result = resolution.OverloadResolutionResult;
                if (result != null)
                {
                    if (result.Succeeded)
                    {
                        var method = result.BestResult.Member;
                        Debug.Assert((object)method != null);
                        if (resolution.MethodGroup.IsExtensionMethodGroup)
                        {
                            Debug.Assert(method.IsExtensionMethod);

                            var thisParameter = method.Parameters[0];
                            if (!thisParameter.Type.IsReferenceType)
                            {
                                // Extension method '{0}' defined on value type '{1}' cannot be used to create delegates
                                diagnostics.Add(
                                    ErrorCode.ERR_ValueTypeExtDelegate,
                                    expr.Syntax.Location,
                                    method,
                                    thisParameter.Type);
                                hasErrors = true;
                            }
                        }
                        else if (method.OriginalDefinition.ContainingType.SpecialType == SpecialType.System_Nullable_T && !method.IsOverride)
                        {
                            // CS1728: Cannot bind delegate to '{0}' because it is a member of 'System.Nullable<T>'
                            diagnostics.Add(
                                ErrorCode.ERR_DelegateOnNullable,
                                expr.Syntax.Location,
                                method);
                            hasErrors = true;
                        }
                    }
                    else if (!hasErrors &&
                            !resolution.IsEmpty &&
                            resolution.ResultKind == LookupResultKind.Viable)
                    {
                        var overloadDiagnostics = DiagnosticBag.GetInstance();

                        result.ReportDiagnostics(binder, expr.Syntax.Location, overloadDiagnostics,
                            expr.Name,
                            resolution.MethodGroup.Receiver, resolution.AnalyzedArguments, resolution.MethodGroup.Methods.ToImmutable(),
                            typeContainingConstructor: null, delegateTypeBeingInvoked: null, isMethodGroupConversion: true);

                        if (!overloadDiagnostics.IsEmptyWithoutResolution)
                        {
                            hasErrors = overloadDiagnostics.HasAnyErrors();
                            diagnostics.AddRange(overloadDiagnostics);
                        }

                        overloadDiagnostics.Free();
                    }
                }
            }

            resolution.Free();
            return hasErrors;
        }

 /// <summary>
 /// Resolve method group based on the optional delegate invoke method.
 /// If the invoke method is null, ignore arguments in resolution.
 /// </summary>
 private static MethodGroupResolution ResolveDelegateMethodGroup(Binder binder, BoundMethodGroup source, MethodSymbol delegateInvokeMethodOpt, ref HashSet<DiagnosticInfo> useSiteDiagnostics)
 {
     if ((object)delegateInvokeMethodOpt != null)
     {
         var analyzedArguments = new AnalyzedArguments();
         GetDelegateArguments(source.Syntax, analyzedArguments, delegateInvokeMethodOpt.Parameters, binder.Compilation);
         var resolution = binder.ResolveMethodGroup(source, analyzedArguments, isMethodGroupConversion: true, inferWithDynamic: true, useSiteDiagnostics: ref useSiteDiagnostics);
         return resolution;
     }
     else
     {
         return binder.ResolveMethodGroup(source, null, isMethodGroupConversion: true, useSiteDiagnostics: ref useSiteDiagnostics);
     }
 }

        /// <summary>
        /// This method is a wrapper around MethodGroupConversionHasErrors.  As a preliminary step,
        /// it checks whether a conversion exists.
        /// </summary>
        private bool MethodGroupConversionDoesNotExistOrHasErrors(
            BoundMethodGroup boundMethodGroup,
            NamedTypeSymbol delegateType,
            Location delegateMismatchLocation,
            DiagnosticBag diagnostics,
            out Conversion conversion)
        {
            if (ReportDelegateInvokeUseSiteDiagnostic(diagnostics, delegateType, delegateMismatchLocation))
            {
                conversion = Conversion.NoConversion;
                return true;
            }

            HashSet<DiagnosticInfo> useSiteDiagnostics = null;
            conversion = Conversions.GetMethodGroupConversion(boundMethodGroup, delegateType, ref useSiteDiagnostics);
            diagnostics.Add(delegateMismatchLocation, useSiteDiagnostics);
            if (!conversion.Exists)
            {
                // No overload for '{0}' matches delegate '{1}'
                diagnostics.Add(ErrorCode.ERR_MethDelegateMismatch, delegateMismatchLocation, boundMethodGroup.Name, delegateType);
                return true;
            }
            else
            {
                Debug.Assert(conversion.IsValid); // i.e. if it exists, then it is valid.
                // Only cares about nullness and type of receiver, so no need to worry about BoundTypeOrValueExpression.
                return this.MethodGroupConversionHasErrors(boundMethodGroup.Syntax, conversion, boundMethodGroup.ReceiverOpt, conversion.IsExtensionMethod, delegateType, diagnostics);
            }
        }

        private static BoundMethodGroup FixMethodGroupWithTypeOrValue(BoundMethodGroup group, Conversion conversion, DiagnosticBag diagnostics)
        {

            if (!IsMethodGroupWithTypeOrValueReceiver(group))
            {
                return group;
            }

            BoundExpression receiverOpt = group.ReceiverOpt;
            Debug.Assert(receiverOpt != null);
            Debug.Assert((object)conversion.Method != null);
            receiverOpt = ReplaceTypeOrValueReceiver(receiverOpt, conversion.Method.IsStatic && !conversion.IsExtensionMethod, diagnostics);
            return group.Update(
                group.TypeArgumentsOpt,
                group.Name,
                group.Methods,
                group.LookupSymbolOpt,
                group.LookupError,
                group.Flags,
                receiverOpt, //only change
                group.ResultKind);
        }

 public override BoundNode VisitMethodGroup(BoundMethodGroup node)
 {
     // We only get here in error cases, as normally the enclosing node is a method group conversion
     // whose visit (below) doesn't call this.  So we don't know which method is to be selected, and
     // therefore don't know if the receiver is used. Assume if the receiver was provided, it is used.
     var receiverOpt = node.ReceiverOpt;
     if (receiverOpt != null)
     {
         return VisitSyntaxWithReceiver(node.Syntax, receiverOpt);
     }
     return null;
 }

 public override Conversion GetMethodGroupConversion(BoundMethodGroup source, TypeSymbol destination, ref HashSet<DiagnosticInfo> useSiteDiagnostics)
 {
     // Conversions involving method groups require a Binder.
     throw ExceptionUtilities.Unreachable;
 }

        private BoundNode VisitMethodGroup(BoundMethodGroup node, bool parentIsConversion)
        {
            // Formerly reported ERR_MemGroupInExpressionTree when this occurred, but the expanded 
            // ERR_LambdaInIsAs makes this impossible (since the node will always be wrapped in
            // a failed conversion).
            Debug.Assert(!(!parentIsConversion && _inExpressionLambda));

            if (_inExpressionLambda && (node.LookupSymbolOpt as MethodSymbol)?.MethodKind == MethodKind.LocalFunction)
            {
                Error(ErrorCode.ERR_ExpressionTreeContainsLocalFunction, node);
            }

            CheckReceiverIfField(node.ReceiverOpt);
            return base.VisitMethodGroup(node);
        }

        private static TypeSymbol MethodGroupReturnType(Binder binder, BoundMethodGroup source, ImmutableArray<ParameterSymbol> delegateParameters, ref HashSet<DiagnosticInfo> useSiteDiagnostics)
        {
            var analyzedArguments = AnalyzedArguments.GetInstance();
            Conversions.GetDelegateArguments(source.Syntax, analyzedArguments, delegateParameters, binder.Compilation);

            var resolution = binder.ResolveMethodGroup(source, analyzedArguments, isMethodGroupConversion: true, useSiteDiagnostics: ref useSiteDiagnostics);

            TypeSymbol type = null;

            // The resolution could be empty (e.g. if there are no methods in the BoundMethodGroup).
            if (!resolution.IsEmpty)
            {
                var result = resolution.OverloadResolutionResult;
                if (result.Succeeded)
                {
                    type = result.BestResult.Member.ReturnType;
                }
            }

            analyzedArguments.Free();
            resolution.Free();
            return type;
        }

        private BoundNode VisitMethodGroup(BoundMethodGroup node, bool parentIsConversion)
        {
            // Formerly reported ERR_MemGroupInExpressionTree when this occurred, but the expanded 
            // ERR_LambdaInIsAs makes this impossible (since the node will always be wrapped in
            // a failed conversion).
            Debug.Assert(!(!parentIsConversion && _inExpressionLambda));

            CheckReceiverIfField(node.ReceiverOpt);
            return base.VisitMethodGroup(node);
        }