PHP FFI::cdef for a C++ function

Question

Since SWIG 4.x is no longer generating PHP wrappers I am trying to interface to the shared library using PHP FFI for openbabel. I wanted to start with something simple so I wanted to just retrieve the version of the library.

** My first question should be can I use FFI to call a C++ shared library?

I tried the following, but it didn't work. Any suggestions?

try {
    $ffi = FFI::cdef(
        "std::string OBReleaseVersion();",
        "/var/www/html/libopenbabel.so");
} catch (Throwable $e) {
    var_dump($e);
}

The base.h file contains

#include <openbabel/babelconfig.h>

namespace OpenBabel
{
  ...
  OBAPI std::string OBReleaseVersion();
  ...
}

The babelconfig.h contains the definition for OBAPI

// If we are using a recent GCC version with visibility support use it
#ifdef HAVE_GCC_VISIBILITY
  #define OB_EXPORT __attribute__ ((visibility("default")))
  #define OB_IMPORT __attribute__ ((visibility("default")))
  #define OB_HIDDEN __attribute__ ((visibility("hidden")))
#elif defined(WIN32) && defined(USING_DYNAMIC_LIBS) && !defined(__MINGW32__)
 #define OB_EXPORT __declspec(dllexport)
 #define OB_IMPORT __declspec(dllimport)
 #define OB_HIDDEN
#else
 #define OB_EXPORT
 #define OB_IMPORT
 #define OB_HIDDEN
#endif

/* Used to export symbols for DLL / shared library builds */
#if defined(MAKE_OBDLL) // e.g. in src/main.cpp
 #ifndef OB_EXTERN
  #define OB_EXTERN   OB_EXPORT extern
 #endif
 #ifndef OBAPI
  #define OBAPI    OB_EXPORT
 #endif
 #ifndef OBCOMMON
  #define OBCOMMON OB_EXPORT
 #endif
 #ifndef OBCONV
  #define OBCONV   OB_EXPORT
 #endif
 #ifndef OBERROR
  #define OBERROR  OB_EXPORT
 #endif
 #ifndef OBFPRT
  #define OBFPRT   OB_EXPORT
 #endif
 #ifndef OBFPTR
  #define OBFPTR   OB_EXPORT
 #endif
 #ifndef OBMCDL
  #define OBMCDL   OB_EXPORT
 #endif
 #ifndef OBDEPICT
  #define OBDEPICT OB_EXPORT
 #endif

#else   // defined(MAKE_OBDLL)

 #ifndef OB_EXTERN
  #define OB_EXTERN   OB_IMPORT extern
 #endif
 #ifndef OBAPI
  #define OBAPI    OB_IMPORT
 #endif
 #ifndef OBCOMMON
  #define OBCOMMON OB_IMPORT
 #endif
 #ifndef OBCONV
  #define OBCONV   OB_IMPORT
 #endif
 #ifndef OBERROR
  #define OBERROR  OB_IMPORT
 #endif
 #ifndef OBFPRT
  #define OBFPRT   OB_IMPORT
 #endif
 #ifndef OBFPTR
  #define OBFPTR   OB_IMPORT
 #endif
 #ifndef OBMCDL
 #define OBMCDL    OB_IMPORT
  #ifndef OBDEPICT
 #define OBDEPICT  OB_IMPORT
 #endif

 #endif

#endif