make ISNAN call a function when in C++ code, in case isnan is a macro

git-svn-id: https://svn.r-project.org/R/trunk@32538 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: tlumley

NEWS

@@ -288,6 +288,9 @@ C-LEVEL FACILITIES
     o	Added an onExit() function to graphics devices, to be executed
 	upon user break if non-NULL.
 
+    o   ISNAN now works even in C++ code that undefines the 
+        isnan macro. 
+
 
 DEPRECATED & DEFUNCT
 

src/include/R_ext/Arith.h

@@ -51,8 +51,18 @@ int R_finite(double);		/* True if none of NA, NaN, +/-Inf */
 
 #define ISNA(x)	       R_IsNA(x)
 /* True for *both* NA and NaN.
-   NOTE: some systems do not return 1 for TRUE. */
-#define ISNAN(x)       (isnan(x)!=0)
+   NOTE: some systems do not return 1 for TRUE. 
+   Also note that C++ math headers specifically undefine
+   isnan if it is a macro (it is on OS X and in C99),
+   hence the workaround.  This code also appears in Rmath.h
+*/
+#ifdef __cplusplus
+  int R_isnancpp(double); /* in arithmetic.c */
+#  define ISNAN(x)     R_isnancpp(x)
+#else
+#  define ISNAN(x)     (isnan(x)!=0)
+#endif
+
 #ifdef HAVE_WORKING_ISFINITE
 /* isfinite is defined in <math.h> according to C99 */
 # define R_FINITE(x)    isfinite(x)

src/include/Rmath.h0.in

@@ -581,7 +581,15 @@ double	gamma_cody(double);
 #ifdef MATHLIB_STANDALONE
 #ifndef MATHLIB_PRIVATE_H
 
-# define ISNAN(x) (isnan(x)!=0)
+/* If isnan is a macro, as C99 specifies, the C++
+   math header will undefine it. This happens on OS X */
+#ifdef __cplusplus
+  int R_isnancpp(double); /* in mlutils.c */
+#  define ISNAN(x)     R_isnancpp(x)
+#else
+#  define ISNAN(x)     (isnan(x)!=0)
+#endif
+
 
 /* We don't have config information available to do anything else */
 #define R_FINITE(x)    R_finite(x)

src/main/arithmetic.c

@@ -131,6 +131,16 @@ int R_IsNaN(double x)
     return 0;
 }
 
+/* ISNAN uses isnan, which is undefined by C++ headers 
+   This workaround is called only when ISNAN() is used
+   in a user code in a file with __cplusplus defined */
+
+int R_isnancpp(double x)
+{
+   return (isnan(x)!=0);
+}
+
+
 /* <FIXME> Simplify this mess.  Not used inside R 
    if isfinite works, and if finite works only in packages */
 int R_finite(double x)

src/nmath/mlutils.c

@@ -54,6 +54,14 @@ int R_finite(double x)
 #endif
 }
 
+/* C++ math header undefines any isnan macro. This file
+   doesn't get C++ headers and so is safe. */
+int R_isnancpp(double x)
+{
+	return (isnan(x) != 0);
+
+}
+
 static double myfmod(double x1, double x2)
 {
     double q = x1 / x2;