error: use of undeclared identifier 'M_PI'

[yuri@FreeBSD]

/usr/ports/misc/iio-oscilloscope/work/iio-oscilloscope-0.16-master/oscplot.c:898:20: error: use of undeclared identifier 'M_PI'
                double a = 2.0 * M_PI / (n - 1);
                                 ^
/usr/ports/misc/iio-oscilloscope/work/iio-oscilloscope-0.16-master/oscplot.c:909:14: error: use of undeclared identifier 'M_PI'
                double a = M_PI * j / (n - 1);
                           ^

Removing -D_POSIX_C_SOURCE=200809L removes these errors.

Version: 0.16
clang-15
FreeBSD 13.2

[Jorge Marques]

M_PI is defined in the the math.h header, check if your system defines them somewhere like /usr/include/math.h, and if CMake is including the system headers properly.

[yuri@FreeBSD]

This looks like a system headers error.

Thank you for your help.

[Dan Nechita]

Closing this, then.