COMPILER macro redefinition in _compiler.c

[pllim]

Description

When doing development work on Windows, I see a warning about 'COMPILER': macro redefinition when I build astropy from source. Probably harmless?

Expected behavior

No redefinition of COMPILER macro in C.

Actual behavior

Searching for cython>=0.29.13
Best match: cython 0.29.13
Processing cython-0.29.13-py3.7-win-amd64.egg

Using ...\astropy\.eggs\cython-0.29.13-py3.7-win-amd64.egg
running test
installing to temporary directory: ...
_compiler.c
astropy\_compiler.c(58): warning C4005: 'COMPILER': macro redefinition
c:\...\envs\py37\include\pyconfig.h(126): note: see previous definition of 'COMPILER'
   Creating library ...\astropy\compiler_version.cp37-win_amd64.lib and
   object ...\astropy\compiler_version.cp37-win_amd64.exp
Generating code
Finished generating code

_compiler.c

#include <Python.h>

/***************************************************************************
 * Macros for determining the compiler version.
 *
 * These are borrowed from boost, and majorly abridged to include only
 * the compilers we care about.
 ***************************************************************************/

#define STRINGIZE(X) DO_STRINGIZE(X)
#define DO_STRINGIZE(X) #X

#if defined __clang__
/*  Clang C++ emulates GCC, so it has to appear early. */
#    define COMPILER "Clang version " __clang_version__

#elif defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)
/* Intel */
#    if defined(__INTEL_COMPILER)
#        define INTEL_VERSION __INTEL_COMPILER
#    elif defined(__ICL)
#        define INTEL_VERSION __ICL
#    elif defined(__ICC)
#        define INTEL_VERSION __ICC
#    elif defined(__ECC)
#        define INTEL_VERSION __ECC
#    endif
#    define COMPILER "Intel C compiler version " STRINGIZE(INTEL_VERSION)

#elif defined(__GNUC__)
/* gcc */
#    define COMPILER "GCC version " __VERSION__

#elif defined(__SUNPRO_CC)
/* Sun Workshop Compiler */
#    define COMPILER "Sun compiler version " STRINGIZE(__SUNPRO_CC)

#elif defined(_MSC_VER)
/* Microsoft Visual C/C++
   Must be last since other compilers define _MSC_VER for compatibility as well */
#    if _MSC_VER < 1200
#        define COMPILER_VERSION 5.0
#    elif _MSC_VER < 1300
#        define COMPILER_VERSION 6.0
#    elif _MSC_VER == 1300
#        define COMPILER_VERSION 7.0
#    elif _MSC_VER == 1310
#        define COMPILER_VERSION 7.1
#    elif _MSC_VER == 1400
#        define COMPILER_VERSION 8.0
#    elif _MSC_VER == 1500
#        define COMPILER_VERSION 9.0
#    elif _MSC_VER == 1600
#        define COMPILER_VERSION 10.0
#    else
#        define COMPILER_VERSION _MSC_VER
#    endif
#    define COMPILER "Microsoft Visual C++ version " STRINGIZE(COMPILER_VERSION)

#else
/* Fallback */
#    define COMPILER "Unknown compiler"

#endif


/***************************************************************************
 * Module-level
 ***************************************************************************/

struct module_state {
/* The Sun compiler can't handle empty structs */
#if defined(__SUNPRO_C) || defined(_MSC_VER)
    int _dummy;
#endif
};

static struct PyModuleDef moduledef = {
    PyModuleDef_HEAD_INIT,
    "compiler_version",
    NULL,
    sizeof(struct module_state),
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

#define INITERROR return NULL

PyMODINIT_FUNC
PyInit_compiler_version(void)


{
  PyObject* m;

  m = PyModule_Create(&moduledef);

  if (m == NULL)
    INITERROR;

  PyModule_AddStringConstant(m, "compiler", COMPILER);

  return m;
}

System Details

Windows-10-10.0.18362-SP0
Python 3.7.1 | packaged by conda-forge | (default, Nov 13 2018, 19:01:41) [MSC v.1900 64 bit (AMD64)]
Numpy 1.16.3
Scipy 1.1.0
astropy 4.0.dev26224

[MSeifert04]

I've also seen this before. Do you happen to know the definition before (python) and after (ours)?

[bsipocz]

(off topic, but I totally forgot about this label of ours :) )

[pllim]

@MSeifert04 , "ours" is the one defined in _compiler.c above. Here is the one from pyconfig.h:

/* set the COMPILER */
#ifdef MS_WIN64
#if defined(_M_X64) || defined(_M_AMD64)
#if defined(__INTEL_COMPILER)
#define COMPILER ("[ICC v." _Py_STRINGIZE(__INTEL_COMPILER) " 64 bit (amd64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
#else
#define COMPILER _Py_PASTE_VERSION("64 bit (AMD64)")
#endif /* __INTEL_COMPILER */
#define PYD_PLATFORM_TAG "win_amd64"
#else
#define COMPILER _Py_PASTE_VERSION("64 bit (Unknown)")
#endif
#endif /* MS_WIN64 */

And it is provided by CPython manually at https://github.com/python/cpython/blob/master/PC/pyconfig.h