features.h

[Stepan Kasal]

Hallo,
    I've found this:  with -D_XOPEN_SOURCE the M_PI & friends are defined
in math.h.  With -D_XOPEN_SOURCE_EXTENDED these are not defined.

    This is counterintuitive: one would expect that _XOPEN_SOURCE is subset
of _XOPEN_SOURCE_EXTENDED .  In other words, I'd expect that __USE_XOPEN
will be defined under -D_XOPEN_SOURCE_EXTENDED .

    I'd expect somethig like the code below to be in features.h .

Sorry if this isn't mistake but necessary feature and I only waste your time.

Stepan

--- /usr/include/features.h	Thu Jul 22 23:29:36 1999
+++ features.h	Wed Feb  2 16:30:02 2000
@@ -164,6 +164,10 @@
 # endif
 #endif
 
+#if defined _XOPEN_SOURCE_EXTENDED && !defined _XOPEN_SOURCE
+# define _XOPEN_SOURCE	1
+#endif
+
 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 # define __USE_POSIX	1