Mex Fortran with nagfor, only calls functions

Question

I am trying something that is not supported. I want to use the NAG Fortran compiler (release 5.3.1) to mex a Fortran file.

Using the command:

nagfor -ideclient -abi=64 -compatible -fpp -I"C:\Program Files\MATLAB\R2013b\extern\include" -Wl,-shared -thread_safe -L"C:\Program Files\MATLAB\R2013b\bin\win64" timesto.F -lmx -lmex -lmat -o timesto.mexw64

I am able to compile and link an adapted version of the timestwo.F Fortran example.

I used the very simple code below and this works well.

#include "fintrf.h"
  subroutine mexFunction(nlhs, plhs, nrhs, prhs)
C     Declarations
  implicit none
C     mexFunction arguments:
  mwPointer plhs(*), prhs(*)
  integer nlhs, nrhs
  call mexEvalString('why')
  end

Notice that mexEvalString is a function.

If I now change

  call mexEvalString('why')

into

  call mexErrMsgTxt('why')

The compilation still works. However, Matlab crashes without giving any indication why.

The only difference I see between both statements is that one contains a subroutine instead of a function.

What is going wrong and how do I fix this?