Issue#114: check for the presence of isnan and isinf, and provide compat macros on MSCV where _isnan and _finite exist instead.

config.h.in

@@ -3,6 +3,22 @@
 /* Define if .gnu.warning accepts long strings. */
 #undef HAS_GNU_WARNING_LONG
 
+/* Define to 1 if you have the declaration of `isinf', and to 0 if you don't.
+   */
+#undef HAVE_DECL_ISINF
+
+/* Define to 1 if you have the declaration of `isnan', and to 0 if you don't.
+   */
+#undef HAVE_DECL_ISNAN
+
+/* Define to 1 if you have the declaration of `_finite', and to 0 if you
+   don't. */
+#undef HAVE_DECL__FINITE
+
+/* Define to 1 if you have the declaration of `_isnan', and to 0 if you don't.
+   */
+#undef HAVE_DECL__ISNAN
+
 /* Define to 1 if you have the <dlfcn.h> header file. */
 #undef HAVE_DLFCN_H
 

configure.ac

@@ -3,7 +3,7 @@ AC_PREREQ(2.52)
 # Process this file with autoconf to produce a configure script.
 AC_INIT([json-c], 0.11.99, [json-c@googlegroups.com])
 
-AM_INIT_AUTOMAKE(AC_PACKAGE_NAME, AC_PACKAGE_VERSION)
+AM_INIT_AUTOMAKE
 
 AC_PROG_MAKE_SET
 
@@ -29,6 +29,10 @@ AC_FUNC_MEMCMP
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_CHECK_FUNCS(strcasecmp strdup strerror snprintf vsnprintf vasprintf open vsyslog strncasecmp setlocale)
+AC_CHECK_DECLS([isnan], [], [], [[#include <math.h>]])
+AC_CHECK_DECLS([isinf], [], [], [[#include <math.h>]])
+AC_CHECK_DECLS([_isnan], [], [], [[#include <float.h>]])
+AC_CHECK_DECLS([_finite], [], [], [[#include <float.h>]])
 
 #check if .section.gnu.warning accepts long strings (for __warn_references)
 AC_LANG_PUSH([C])

json_object.c

@@ -27,6 +27,7 @@
 #include "json_object.h"
 #include "json_object_private.h"
 #include "json_util.h"
+#include "math_compat.h"
 
 #if !defined(HAVE_STRDUP) && defined(_MSC_VER)
   /* MSC has the version as _strdup */

math_compat.h

@@ -0,0 +1,20 @@
+#ifndef __math_compat_h
+#define __math_compat_h
+
+/* Define isnan and isinf on Windows/MSVC */
+
+#ifndef HAVE_DECL_ISNAN
+# ifdef HAVE_DECL__ISNAN
+#include <float.h>
+#define isnan(x) _isnan(x)
+# endif
+#endif
+
+#ifndef HAVE_DECL_ISINF
+# ifdef HAVE_DECL__FINITE
+#include <float.h>
+#define isinf(x) (!_finite(x))
+# endif
+#endif
+
+#endif