Fortran IO read size inconsistent

[lsawade]

Describe the bug

specfem_setup.hpp defines sizes of some numbers:

using type_real = float;
const static int ndim{ 2 };
const static int fint{ 4 }, fdouble{ 8 }, fbool{ 4 }, fchar{ 512 };

and fortran_read_value(type_real *value, ....) is defined as follows.

void specfem::IO::fortran_read_value(type_real *value, std::ifstream &stream,
                                     int &buffer_length) {

  buffer_length -= fdouble;         // <-------------------------
  char *ivalue = new char[fdouble]; // <-------------------------
  if (buffer_length < 0) {
    throw std::runtime_error("Error reading fortran file in type_real");
  }
  stream.read(ivalue, freal);
  *value = *reinterpret_cast<type_real *>(ivalue);
  delete[] ivalue;
  return;
}

This worked for meshfem2d (fortran) because the "in-repo"'s mesher has CUSTOM_REAL set to SIZE_DOUBLE aka 8.

** Solution **

Here, we really want to define the the parameters using enable_double_precision in the cmake file.

Fix the 2d meshing and reading thereof by assuming a double?

using type_real = float;
const static int ndim{ 2 };
const static int fint{ 4 }, ffloat{ 4 }, fdouble{ 8 }, fbool{ 4 }, fchar{ 512 };
constexpr static int freal = sizeof(type_real);

And as a consequence:

...
void fortran_read_value(type_real *value, std::ifstream &stream,
                        int &buffer_length);
#if freal != ffloat
void fortran_read_value(float *value, std::ifstream &stream, int &buffer_length);
#else
void fortran_read_value(double *value, std::ifstream &stream, int &buffer_length);
#endif
void fortran_read_value(int *value, std::ifstream &stream, int &buffer_length);
...