Hi Paul, all,
> I want 'make' to fail if any module
> uses ctime, since it's asking for trouble in portable code (it has
> undefined behavior with out-of-range time stamps). I suppose someone
> could write code that carefully bounds the time stamps and then uses
> ctime; such code can "#undef ctime" if it really wants to.
This was the initial approach we took three weeks ago. But it didn't
work out because people do things like
#ifdef __linux__
s = ctime (tp);
#else
...
#endif
and it's not a bug for them to do so. See the thread at
http://lists.gnu.org/archive/html/bug-gnulib/2007-02/msg00000.html
or your example from coreutils
http://lists.gnu.org/archive/html/bug-gnulib/2007-02/msg00037.html
So, we need to foresee some tolerance against purposeful uses of unportable
functions. Either warnings, or - if using errors - a way to disable the
errors in a way that is less intrusive than "#undef ctime".
Paul Eggert wrote:
> I'd rather not have a warning, as there are too many false alarms.
> ...
> I want the 'make'
> to fail if someone is using a function that should not be used.
Ok, probably we need to discuss the use cases from scratch.
The use case I have in mind is someone who has written a program that
compiles fine with "gcc -Wall", and he wants to make it portable, but
he does not have time or the means to test it on all system from AIX to
z/OS. I want to tell him the following in the gnulib manual:
"For testing portability, invoke 'gnulib-tool --import check-portability'
(or check-portability-unix if mingw is not among your portability targets),
then compile the program and look at the link time warnings. Use
gnulib-tool --import with all the mentioned modules; all portability
warnings will then disappear, and your program will be portable."
The 'check-portability' module would be implemented as a module that defines
GNULIB_POSIXCHECK and has dependencies on 'string', 'stdio', 'time' etc.
What precisely is the use case that you imagine? You want errors for the
same purpose as the one people use "-Werror" for, namely to check that no
new dependencies are introduced in an existing program?
Bruno
