M_PI not defined

[micheltallon]

Error in compilation on Linux Mint 20.2 (Uma).

ipy.c: In function Y_ipy_init:
ipy.c:439:33: error: M_PI undeclared (first use in this function)
  439 |   define_double_const("IPY_PI", M_PI);
      |                                 ^~~~

This is solved by adding this line in ipy.c

#define __USE_MISC /* For M_PI */

This is because in math.h M_PI is now guarded:

#if defined __USE_MISC || defined __USE_XOPEN
[...]
# define M_PI           3.14159265358979323846  /* pi */
[...]
#endif

Cheers
Michel

[micheltallon]

Actually setting __USE_XOPEN seems more general than __USE_MISC.
Indeed on Ubuntu 14.04.5, we get:

#if defined __USE_BSD || defined __USE_XOPEN
[...]
# define M_PI           3.14159265358979323846  /* pi */
[...]
#endif

[emmt]

Shoulde be solved by commit 393fbe3.