On Sat, Jul 28, 2018 at 1:06 PM, Konstantin Belousov <kostik...@gmail.com> wrote: > On Sat, Jul 28, 2018 at 07:08:00PM +0000, Conrad Meyer wrote: >> For unclear reasons, POSIX' definition of these routines spells NULL as >> "(char *)0." This is needlessly unclear. One guess might be that POSIX >> targets more exotic computer architectures than FreeBSD does. Fortunately, >> there is no such problem on any reasonable platform for FreeBSD to support. >> Spell NULL as NULL. > > The reasons are quite clear.
Unclear here refers to the lack of documentation, not the absense of a possible explanation. > Practically NULL has to be defined as '0' > or '0L' at best, for C and esp. C++ rules of the pointers automatic > casts to work. This means that NULL cannot be used in vararg lists where > the pointer is expected. This is not true on FreeBSD. NULL is (void*)0 in all C code, and the special nullptr value in C++. Yes, this is a stronger definition than the C standard guarantees. This is because the C standard permits much more exotic architectures than FreeBSD actually runs on. > In other words, the (char *)0 part of the pre-commit text was correct, > while after-commit use of NULL only works on machines where pointers > have the same representation as ints or longs. I believe this encompasses all architectures FreeBSD supports — even ignoring our sys/_null.h definition of NULL as (void *)0 or nullptr. Best, Conrad _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
