ArgumentException when calling Count() method from object returned by dynamic

[alser]

• DynamicExpresso.Core 2.17.1
• .NET 8.0

Issue is reproduced in following default console template:

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
    </PropertyGroup>

    <ItemGroup>
      <PackageReference Include="DynamicExpresso.Core" Version="2.17.1" />
    </ItemGroup>

</Project>

using System.Dynamic;
using DynamicExpresso;

var interpreter = new Interpreter();
var expr = interpreter.Parse("p.Value.Count()", new Parameter("p", typeof(SampleParameter)));
var result = expr.Invoke(new SampleParameter());

Console.WriteLine($"Result: {result}");

public sealed class SampleClass
{
    public int Count() => 42;
}

public sealed class SampleParameter : DynamicObject
{
    public override bool TryGetMember(GetMemberBinder binder, out object? result)
    {
        switch (binder.Name)
        {
            case "Value":
                result = new SampleClass();
                return true;

            default:
                result = null;
                return false;
        }
    }
}

Here we have parameter SampleParameter which is a dynamic object. Its dynamic property Value returns some other non-dynamic object SampleClass, which in turn has method named Count().

Trying to parse expression like "p.Value.Count()" results in exception:

System.ArgumentException: Type System.Collections.Generic.IEnumerable`1[TSource] contains generic parameters (Parameter 'type')
   at System.Dynamic.Utils.TypeUtils.ValidateType(Type type, String paramName, Int32 index)
   at System.Dynamic.Utils.TypeUtils.ValidateType(Type type, String paramName, Boolean allowByRef, Boolean allowPointer)
   at System.Linq.Expressions.Expression.Convert(Expression expression, Type type, MethodInfo method)
   at DynamicExpresso.Resolution.ExpressionUtils.PromoteExpression(Expression expr, Type type, Boolean exact)
   at DynamicExpresso.Resolution.MethodResolution.CheckIfMethodIsApplicableAndPrepareIt(MethodData method, Expression[] args)
   at DynamicExpresso.Resolution.MethodResolution.<>c__DisplayClass1_0.<FindBestMethod>b__0(MethodData m)
   at System.Linq.Enumerable.WhereEnumerableIterator`1.ToArray()
   at DynamicExpresso.Resolution.MethodResolution.FindBestMethod(IEnumerable`1 methods, Expression[] args)
   at DynamicExpresso.Resolution.MethodResolution.FindBestMethod(IEnumerable`1 methods, Expression[] args)
   at DynamicExpresso.Reflection.MemberFinder.FindExtensionMethods(String methodName, Expression[] args)
   at DynamicExpresso.Parsing.Parser.ParseExtensionMethodInvocation(Type type, Expression instance, Int32 errorPos, String id, Expression[] args)
   at DynamicExpresso.Parsing.Parser.ParseMethodInvocation(Type type, Expression instance, Int32 errorPos, String methodName, TokenId open, String openExpected, TokenId close, String closeExpected)
   at DynamicExpresso.Parsing.Parser.ParseMethodInvocation(Type type, Expression instance, Int32 errorPos, String methodName)
   at DynamicExpresso.Parsing.Parser.ParseMemberAccess(Type type, Expression instance)
   at DynamicExpresso.Parsing.Parser.ParseMemberAccess(Expression instance)
   at DynamicExpresso.Parsing.Parser.ParsePrimary()
   at DynamicExpresso.Parsing.Parser.ParseUnary()
   at DynamicExpresso.Parsing.Parser.ParseMultiplicative()
   at DynamicExpresso.Parsing.Parser.ParseAdditive()
   at DynamicExpresso.Parsing.Parser.ParseShift()
   at DynamicExpresso.Parsing.Parser.ParseTypeTesting()
   at DynamicExpresso.Parsing.Parser.ParseComparison()
   at DynamicExpresso.Parsing.Parser.ParseLogicalAnd()
   at DynamicExpresso.Parsing.Parser.ParseLogicalXor()
   at DynamicExpresso.Parsing.Parser.ParseLogicalOr()
   at DynamicExpresso.Parsing.Parser.ParseConditionalAnd()
   at DynamicExpresso.Parsing.Parser.ParseConditionalOr()
   at DynamicExpresso.Parsing.Parser.ParseConditional()
   at DynamicExpresso.Parsing.Parser.ParseAssignment()
   at DynamicExpresso.Parsing.Parser.ParseExpressionSegment()
   at DynamicExpresso.Parsing.Parser.ParseExpressionSegment(Type returnType)
   at DynamicExpresso.Parsing.Parser.Parse()
   at DynamicExpresso.Parsing.Parser.Parse(ParserArguments arguments)
   at DynamicExpresso.Interpreter.ParseAsLambda(String expressionText, Type expressionType, Parameter[] parameters)
   at DynamicExpresso.Interpreter.Parse(String expressionText, Type expressionType, Parameter[] parameters)
   at DynamicExpresso.Interpreter.Parse(String expressionText, Parameter[] parameters)
   at Program.<Main>$(String[] args) in C:\Users\User\RiderProjects\ConsoleApp2\ConsoleApp2\Program.cs:line 5

1. If method Count() renamed to something else (like Count2()), then all is ok, expression p.Value.Count2() successfully returns our magic number.
2. Using DynamicExpresso.Core 2.16.1 no issues occur with Count() method.

It may have something to do with commit 2696232a8dbe1c52371d0a59602e6c9e60ddd781 where condition "expr is DynamicExpression" is added.

[davideicardi]

Thank you for the bug report. I will try to fix it in the future. As usual any help is appreciated.

[davideicardi]

It could be related to #325 .

[metoule]

Yes, the root cause is the same as #325. I'll open a PR to revert the change made in #296

[metoule]

Closing this issue as duplicate of #325