[Python-Dev] C99 code in the Python core?

[Mark Dickinson]

I have a general question and a specific question.  First the general one:

(1) When is it okay to use C99 code in the Python core?  More particularly,
is it considered acceptable to use widely-implemented library functions that
are specified in C99 but not ANSI C, or widely-implemented features that
are new to C99?

Or is C99 code now acceptable pretty much anywhere?  If so, should
PEP 7 be updated?  It currently says: """Use ANSI/ISO standard C
(the 1989 version of the standard)."""

I think there are some C99 features that still aren't implemented
everywhere, even on major platforms.  (Examples are the inverse hyperbolic
trig functions in math.h.)

And the specific question:

(2) Is it okay to use the '%a' format specifier for sprintf, sscanf and friends.
Are there major platforms where this isn't implemented?  (Using
'%a' would make the issue implementation much simpler.)

Mark