Issue #183 breaks compilation of Fortran Bindings + a simple fix

[SciFiShroom]

Hey folks, I've been having some problems compiling the current master version of SuperLU_DIST and I've managed to trace the problem back to a bug introduced a few months ago in response to issue #183 "setenv SUPERLU_MAX_BUFFER_SIZE limited". Luckily, it appears to be an easy fix.

When compiling the Fortran bindings, make is told to compile target f_5x5, which requires the compilation of sp_ienv.c. This is a simple script that only implements one function, sp_ienv_dist. The problem is that there are two versions of sp_ienv.c: One is in SRC/prec-independent, and the other is in FORTRAN. They used to be essentially the same file, but as of the fix for #183 they are quite different, and critically have different return types (the FORTRAN version still returns int instead of the new int_t). By the time make gets to f_5x5 (at 98% compilation completion) it has already compiled both the SRC version as well as superlu_defs.h in SRC/include, which defines the return type of sp_ienv_dist as int_t in accordance with the SRC version of the file. The compiler sees that superlu_defs.h and the FORTRAN version of sp_ienv_dist don't agree on return type, and compilation fails as a result.

/home/marti990/Assembler/auto-installed-dependencies/SuperLU_DIST/superlu_dist-master/FORTRAN/sp_ienv.c:78:1: error: conflicting types for 'sp_ienv_dist'; have 'int(int,  superlu_dist_options_t *)'
   78 | sp_ienv_dist(int ispec, superlu_dist_options_t *options)
      | ^~~~~~~~~~~~
In file included from /home/marti990/Assembler/auto-installed-dependencies/SuperLU_DIST/superlu_dist-master/SRC/include/superlu_ddefs.h:37,
                 from /home/marti990/Assembler/auto-installed-dependencies/SuperLU_DIST/superlu_dist-master/FORTRAN/sp_ienv.c:18:
/home/marti990/Assembler/auto-installed-dependencies/SuperLU_DIST/superlu_dist-master/SRC/include/superlu_defs.h:1105:15: note: previous declaration of 'sp_ienv_dist' with type 'int_t(int,  superlu_dist_options_t *)' {aka 'long int(int,  superlu_dist_options_t *)'}
 1105 | extern int_t  sp_ienv_dist (int, superlu_dist_options_t *);
      |               ^~~~~~~~~~~~
make[2]: *** [FORTRAN/CMakeFiles/f_5x5.dir/build.make:95: FORTRAN/CMakeFiles/f_5x5.dir/sp_ienv.c.o] Error 1

Luckily, it seems sp_ienv.c isn't used very much in the Fortran bindings directory, and I found that simply replacing the file with the SRC version causes compilation to succeed.

Relatedly, it seems that the Python bindings also haven't been updated to reflect the sp_ienv_dist return type change. I'm not using these and have not compiled them, but a cursory grep of the directory reveals that pdbridge.c calls sp_ienv_dist 3 times, two of which assume the old int return type. I'm guessing these would also fail to compile for the same reason.

[xiaoyeli]

We need to update sp_ienv.c. We also made the Python and FORTRAN versions compatible with the new sp_ienv.c.
These are in the Master branch.

cc: @liuyangzhuan