[C++/CLI] [IJW] HRException crash when calling a managed function with 17+ parameters from native code (regression from .NET 8)

[fabricefou]

Description

Calling a managed C++/CLI function with 17 or more parameters from a native C++ executable via IJW (It Just Works) interop throws an unhandled HRException at runtime. The same code works correctly on .NET 8 and works correctly on .NET 10 if the function has 16 or fewer parameters.

Reproduction Steps

1. C++/CLI managed project (CppCliProject.dll) — Functions.hpp:

#pragma once
#include <cstdint>

struct IntWrapper
{
    int Value;
};

class __declspec(dllexport) Functions
{
public:

    int64_t static Sum17(const int& a0,
        const IntWrapper& a1,
        const IntWrapper& a2,
        const IntWrapper& a3,
        const IntWrapper& a4,
        const IntWrapper& a5,
        const IntWrapper& a6,
        const IntWrapper& a7,
        const IntWrapper& a8,
        const IntWrapper& a9,
        const IntWrapper& a10,
        const IntWrapper& a11,
        const IntWrapper& a12,
        const IntWrapper& a13,
        const IntWrapper& a14,
        const IntWrapper& a15,
        const IntWrapper& a16,
        const int& a17);
};

function.cpp

#include "Functions.hpp"

int64_t Functions::Sum17(const int& a0,
	const IntWrapper& a1,
	const IntWrapper& a2,
	const IntWrapper& a3,
	const IntWrapper& a4,
	const IntWrapper& a5,
	const IntWrapper& a6,
	const IntWrapper& a7,
	const IntWrapper& a8,
	const IntWrapper& a9,
	const IntWrapper& a10,
	const IntWrapper& a11,
	const IntWrapper& a12,
	const IntWrapper& a13,
	const IntWrapper& a14,
	const IntWrapper& a15,
	const IntWrapper& a16,
	const int& a17)
{
	System::Console::WriteLine(System::Runtime::InteropServices::RuntimeInformation::FrameworkDescription);
	System::Console::WriteLine(a1.Value);
	System::Console::WriteLine(a2.Value);
	return a1.Value + a2.Value + a3.Value + a4.Value + a5.Value + a6.Value + a7.Value + a8.Value + a9.Value + a10.Value
		+ a11.Value + a12.Value + a13.Value + a14.Value + a15.Value + a16.Value + a17;
}

2. Native C++ executable (ParametersCrashCppCli.exe) — main.cpp:

#include <iostream>
#include "../CppCliProject/Functions.hpp"


int main()
{
	auto value = Functions::Sum17(0, { 1 }, { 2 }, { 3 }, { 4 }, { 5 }, { 6 }, { 7 }, { 8 }, { 9 }, { 10 }, { 11 }, { 12 }, { 13 }, { 14 }, { 15 }, { 16 }, 17);
    std::cout << value << std::endl;
}

ParametersCrashCppCli.zip

Expected behavior

The function executes normally and returns the sum of all 18 arguments (153).

Actual behavior

An unhandled HRException (Microsoft C++ exception) is thrown during the IJW native-to-managed thunk dispatch:

Exception thrown at 0x00007FFE757773FA in ParametersCrashCppCli.exe:
Microsoft C++ exception: HRException at memory location 0x0000008702CFEC38.

Callstack:

KernelBase.dll!00007ffe757773fa
ParametersCrashCppCli.exe!main  [ParametersCrashCppCli.cpp @ line with Sum17 call]
ParametersCrashCppCli.exe!invoke_main
ParametersCrashCppCli.exe!__scrt_common_main_seh

Regression?

yes, works in .NET8

Known Workarounds

reduce number of parameters

Configuration

Environment

Component	Version
.NET Runtime	10.0.5
coreclr.dll	10.0.5 (C:\...\dotnet-sdk\shared\Microsoft.NETCore.App\10.0.5\)
clrjit.dll	10.0.5 (C:\...\dotnet-sdk\shared\Microsoft.NETCore.App\10.0.5\)
Ijwhost.dll	loaded from x64\Debug\Ijwhost.dll
MSVC toolset	14.50.35717
Visual Studio	18 Professional
OS	Windows (x64)
Architecture	x64
Configuration	Debug

Other information

No response

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