complex.c: M_PI in VC

* complex.c (_USE_MATH_DEFINES): needed for M_PI in Microsoft
  Visual C.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49732 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 0 deletions

diff --git a/complex.c b/complex.c
index 9e352a8c39..efba0b34e7 100644
--- a/complex.c
+++ b/complex.c
@@ -6,6 +6,10 @@
 */
 
 #include "internal.h"
+#if defined _MSC_VER
+/* Microsoft Visual C does not define M_PI and others by default */
+# define _USE_MATH_DEFINES 1
+#endif
 #include <math.h>
 
 #define NDEBUG