raw_stream formatter: [Win32] Use std::signbit() if available, instead of _fpclass().

FIXME: It should be generic to C++11. For now, it is dedicated to mingw-w64.
llvm-svn: 199052

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Support/raw_ostream.cpp b/llvm/lib/Support/raw_ostream.cpp
index cb9648981a3..84f5ab592e6 100644
--- a/llvm/lib/Support/raw_ostream.cpp
+++ b/llvm/lib/Support/raw_ostream.cpp
@@ -227,11 +227,17 @@ raw_ostream &raw_ostream::operator<<(double N) {
   // On MSVCRT and compatible, output of %e is incompatible to Posix
   // by default. Number of exponent digits should be at least 2. "%+03d"
   // FIXME: Implement our formatter to here or Support/Format.h!
+#if __cplusplus >= 201103L && defined(__MINGW32__)
+  // FIXME: It should be generic to C++11.
+  if (N == 0.0 && std::signbit(N))
+    return *this << "-0.000000e+00";
+#else
   int fpcl = _fpclass(N);
 
   // negative zero
   if (fpcl == _FPCLASS_NZ)
     return *this << "-0.000000e+00";
+#endif
 
   char buf[16];
   unsigned len;