dotnet/BenchmarkDotNet · error · ArgumentException

Method {methodToCall} should be static method.

Error message

Method {methodToCall} should be static method.

What it means

IlGeneratorCallExtensions.EmitStaticCall is an internal helper used by BenchmarkDotNet's IL emission for generated benchmark assemblies. It requires the supplied MethodInfo to be static; otherwise it throws ArgumentException. End users do not call it directly-it runs during benchmark assembly code generation.

Source

Thrown at src/BenchmarkDotNet/Helpers/Reflection.Emit/IlGeneratorCallExtensions.cs:14

using System.Reflection;
using System.Reflection.Emit;

namespace BenchmarkDotNet.Helpers.Reflection.Emit
{
    internal static class IlGeneratorCallExtensions
    {
        public static void EmitStaticCall(
            this ILGenerator ilBuilder,
            MethodInfo methodToCall,
            params LocalBuilder[] argLocals)
        {
            if (!methodToCall.IsStatic)
                throw new ArgumentException($"Method {methodToCall} should be static method.");

            EmitCallCore(ilBuilder, null, methodToCall, argLocals);
        }

        public static void EmitInstanceCallThisValueOnStack(
            this ILGenerator ilBuilder,
            LocalBuilder optionalLocalThis,
            MethodInfo methodToCall,
            params LocalBuilder[] argLocals) =>
            EmitInstanceCallThisValueOnStack(ilBuilder, optionalLocalThis, methodToCall, argLocals, false);

        public static void EmitInstanceCallThisValueOnStack(
            this ILGenerator ilBuilder,
            LocalBuilder? optionalLocalThis,
            MethodInfo methodToCall,
            IEnumerable<LocalBuilder> argLocals,
            bool forceDirectCall = false)
        {

View on GitHub (pinned to b515068b61)

Solutions

1. Simplify the benchmark method signature to a common supported shape and re-run.
2. Update BenchmarkDotNet to the latest version where codegen edge cases are fixed.
3. If reproducible on the current version, file a BenchmarkDotNet issue with the benchmark that triggers code generation.

try { runner.Run(); }
catch (ArgumentException ex) when (ex.Message.Contains("should be static method")) { /* simplify benchmark, report issue */ }

When it happens

Trigger: The internal IL emitter is asked to emit a static call (call opcode) for a MethodInfo whose IsStatic is false, i.e. an instance method was supplied where a static method was expected.

Common situations: A mismatch inside BenchmarkDotNet's code generator (e.g. awaiting/calling an instance helper as if static), almost always indicating a library bug rather than user misconfiguration. Encountered with unusual benchmark method shapes (async iterators, ref returns, etc.).

Related errors

• The methodToCall should have non-null DeclaringType.
• Method {methodToCall} should be instance method.
• The optionalLocalThis should be null for static calls
• Can not emit base call for {constructorBuilder}
• The constructorBuilder should have non-null DeclaringType.

AI-assisted analysis of dotnet/BenchmarkDotNet@b515068b61 (2026-08-13). Data as JSON: /api/errors/f4a37bb0760bb15d. Report an issue: GitHub.