Mex file compiles in Visual Studio but crashes MATLAB, getting error in debug.

HI Matlab central community. I tried to ask this question in StackOverflow but I could not resolve it. I compile a mex file in VIsual Studio 2013, which is very basic:

#include "mex.h"
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
  mexPrintf("Hello! :)\n");
  return;
}

This compiles as a mexw64 succesfully. I then open up MATLAB v2016a, and try to run mcx() with no input parameters and mcx(cfg) where cfg has 1,2 or 3 parameters. Each different scenario cases MATLAB to crash, end prematurely. I attach visual studio to MATLAB, and I get the error:

'MATLAB.exe' (Win32): Loaded 'C:\Users\tub08918\Google Drive\Patil Lab\AlexsFolderPleaseVisitMe\RamanMonteCarlo\mcx-2017.3-src\mcx\vsproj\mcx\x64\Debug\mcx.mexw64'. Symbols loaded.
First-chance exception at 0x00000000000260A8 in MATLAB.exe: 0xC0000005: Access violation executing location 0x00000000000260A8.
> throw_segv_longjmp_seh_filter()
throw_segv_longjmp_seh_filter(): invoking THROW_SEGV_LONGJMP SEH filter
> throwSegvLongjmpFilter()
MATLAB.exe has triggered a breakpoint.

Now the aim is to compile a file with CUDA capabilities, bu I can't even figure out what is causing this very simple ne-line code to fail. My props file comes from https://github.com/chappjc/MATLAB/tree/master/propertySheets. My build is x64 and I made sure to compile as x64. I tried using a new project that didnt help, so I am out of ideas why this simple code would be compiling as a mex file but failing when called from MATLAB. Interstingly, if I leave mexFunction blank, then MATLAB does not crash. IF I have some easy operations, like 2+2, MATLAB does not failk. It seems to happen when I call any function built into c++ or from mex.h

[Jan]

What is "mcx"? Is this related to http://mcx.sourceforge.net/cgi-bin/index.cgi?Doc/MCXLAB?

[Alexander Dumont]

Yes I am trying to modify the source code

Answer 1

[Philip Borghesani]

First suggestion build with the mex command instead of directly with visual studio. Make sure that works. Then check your compile options against those displayed with mex -v . If this was x32 then I would blame the calling convention, MATLAB requires cdecl default.

Some first chance access violations are expected due to the use of Java. If the mex file works without a debugger attached and continue works (might require multiple and frequent continues... disable first chance access violation checking) then there are no problems with the code.

[Alexander Dumont]

I will try both your suggestions and thank you for being very helpful.

[Alexander Dumont]

So you were right building from MATLAB does not produce any errors and I am able to compile and run with multiple inputs

[Alexander Dumont]

However, VS is still giving me the crippling error.