[PATCH] define M_PI etc. if _XOPEN_SOURCE is defined appropriately

[Jon TURNEY <jon dot turney at dronecode dot org dot uk>]

math.h only defines M_PI and similar constants if __STRICT_ANSI__ is not 
defined.

SUSv2 specifies that math.h should define some of these constants [1].

Attached is a patch to also define these constants if _XOPEN_SOURCE is 
defined appropriately.

$ cat m_pi_test.c
#include <math.h>

int main()
{
  double d = M_PI;
}

before patch:

$ gcc m_pi_test.c

$ gcc -std=c99 m_pi_test.c
m_pi_test.c: In function âmainâ:
m_pi_test.c:5:14: error: âM_PIâ undeclared (first use in this function)

$ gcc -std=c99 m_pi_test.c -D_XOPEN_SOURCE=500
m_pi_test.c: In function âmainâ:
m_pi_test.c:5:14: error: âM_PIâ undeclared (first use in this function)

after patch:

$ gcc m_pi_test.c

$ gcc -std=c99 m_pi_test.c
m_pi_test.c: In function âmainâ:
m_pi_test.c:5:14: error: âM_PIâ undeclared (first use in this function)

$ gcc -std=c99 m_pi_test.c -D_XOPEN_SOURCE=500

2014-07-30  Jon TURNEY  <jon.turney@dronecode.org.uk>

	* libc/include/math.h: Also define M_PI etc. if _XOPEN_SOURCE is
	defined appropriately.

[1] http://pubs.opengroup.org/onlinepubs/007908799/xsh/math.h.html

Attachment: math.h.patch
Description: Text document