Question

I’ve got a COM object wtitten on c#, and i’m using it in a c++ dll.

In c++ the COM object is imported with #import derective

The problem is that when the call is made from a c++ dll to any function of the COM object i’m getting a runtime check error:

Run-Time Check Failure #0 – The value of ESP was not properly saved
across a function call. This is usually a result of calling a
function declared with one calling convention with a function pointer
declared with a different calling convention.

In the com object wrapper generated by c++ import directive, all functions are declared as __stdcall

Answer 1

OK, it looks like I have found the solution:
I have declated In/Out/MarshalAs attributes for all methods in the C# COM interface:

[Guid("EEB4C1AE-4DB2-4bdb-86D4-A429B27496A3")]
public interface IAXFarCards
{
    [DispId(1)]
    void InitDbConnection([In, MarshalAs(UnmanagedType.BStr)] string connectionString);

    [DispId(2)]
    [return: MarshalAs(UnmanagedType.I4)]
    int GetCardInfo(
        [In, MarshalAs(UnmanagedType.BStr)]             string card,
        [In, MarshalAs(UnmanagedType.VariantBool)]      bool   isTemplate,
        [In, MarshalAs(UnmanagedType.I4)]               int    cashDeskId,
        [Out, MarshalAs(UnmanagedType.VariantBool)] out bool   isActive,
        [Out, MarshalAs(UnmanagedType.I4)]          out int    discountNumber,
        [Out, MarshalAs(UnmanagedType.I8)]          out Int64  amount,
        [In, Out, MarshalAs(UnmanagedType.BStr)]    ref string ownerName,
        [In, Out, MarshalAs(UnmanagedType.I4)]      ref int    clientId
        );