B0 define conflicts on Linux with user code

[certik]

Due to this define:

https://github.com/bminor/glibc/blob/0b262ca4c64cd9042576ddb9969607c0ea1187d7/bits/termios.h#L288

user code can break. To fix it, we should but

#undef B0

right after including termios.h. The same for all the other constants.

Reported by @KineticTheory.

[certik]

This seems to be a known problem, e.g.:

http://eigen.tuxfamily.org/bz/show_bug.cgi?id=365

https://www.mit.edu/afs.new/athena/astaff/source/src-8.2/third/tcsh/mi.termios.c

android/ndk#630

linbox-team/fflas-ffpack#57

lvgl/lvgl#941 (comment)

https://gitlab.mech.kuleuven.be/rob-expressiongraphs/luabind/commit/418e4c852dfa027c386153396534ccf079efbfee

Most codes decided to rename B0 to something else to avoid this collision. But the other solution is to simply undefine such a macro.

I also found this note, which lists the reserved names that programs should not use. B0 is among them ("names prefixed with B followed by a digit):

https://www.gnu.org/software/libc/manual/html_node/Reserved-Names.html

[KineticTheory]

This seems to be a known problem, e.g.:

http://eigen.tuxfamily.org/bz/show_bug.cgi?id=365

https://www.mit.edu/afs.new/athena/astaff/source/src-8.2/third/tcsh/mi.termios.c

android/ndk#630

linbox-team/fflas-ffpack#57

littlevgl/lvgl#941 (comment)

https://gitlab.mech.kuleuven.be/rob-expressiongraphs/luabind/commit/418e4c852dfa027c386153396534ccf079efbfee

Most codes decided to rename B0 to something else to avoid this collision. But the other solution is to simply undefine such a macro.

I also found this note, which lists the reserved names that programs should not use. B0 is among them ("names prefixed with B followed by a digit):

https://www.gnu.org/software/libc/manual/html_node/Reserved-Names.html

Wow! Thanks for all of the links. I’ll pass this along.