remove 'clever' NA checks

ChangeLog

@@ -1,3 +1,7 @@
+2017-12-19  Kevin Ushey  <kevinushey@gmail.com>
+
+        * inst/include/Rcpp/internal/na.h: Remove 'clever' NA / NaN checks
+
 2017-12-16  Dirk Eddelbuettel  <edd@debian.org>
 
         * DESCRIPTION (Date, Version): Updated minor version and date

inst/include/Rcpp/internal/na.h

@@ -23,67 +23,6 @@
 namespace Rcpp {
 namespace internal {
 
-// we rely on the presence of unsigned long long types, since we
-// want to compare specific bit patterns, but we can't explicitly
-// assign a hex to a double storage.
-
-#ifdef RCPP_HAS_LONG_LONG_TYPES
-
-#ifdef HAS_STATIC_ASSERT
-static_assert(
-    sizeof(rcpp_ulong_long_type) == sizeof(double),
-    "unsigned long long and double have same size"
-);
-#endif
-
-// motivation: on 32bit architectures, we only see 'LargeNA'
-// as defined ahead; on 64bit architectures, R defaults to
-// 'SmallNA' for R_NaReal, but this can get promoted to 'LargeNA'
-// if a certain operation can create a 'signalling' NA, e.g. NA_real_+1
-static const rcpp_ulong_long_type SmallNA = 0x7FF00000000007A2;
-static const rcpp_ulong_long_type LargeNA = 0x7FF80000000007A2;
-
-struct NACanChange {
-    enum { value = sizeof(void*) == 8 };
-};
-
-template <bool NACanChange>
-bool Rcpp_IsNA__impl(double);
-
-template <>
-inline bool Rcpp_IsNA__impl<true>(double x) {
-    return memcmp(
-        (void*) &x,
-        (void*) &SmallNA,
-        sizeof(double)
-    ) == 0 or memcmp(
-        (void*) &x,
-        (void*) &LargeNA,
-        sizeof(double)
-    ) == 0;
-}
-
-template <>
-inline bool Rcpp_IsNA__impl<false>(double x) {
-    return memcmp(
-        (void*) &x,
-        (void*) &LargeNA,
-        sizeof(double)
-    ) == 0;
-}
-
-inline bool Rcpp_IsNA(double x) {
-    return Rcpp_IsNA__impl< NACanChange::value >(x);
-}
-
-inline bool Rcpp_IsNaN(double x) {
-    return R_IsNaN(x);
-}
-
-#else
-
-// fallback when we don't have unsigned long long
-
 inline bool Rcpp_IsNA(double x) {
     return R_IsNA(x);
 }
@@ -92,7 +31,5 @@ inline bool Rcpp_IsNaN(double x) {
     return R_IsNaN(x);
 }
 
-#endif
-
 }
 }