svn commit: r227487 - head/include

[David Chisnall]

On 14 Nov 2011, at 18:02, David Schultz wrote:

> On Mon, Nov 14, 2011, Dimitry Andric wrote:
>> On 2011-11-14 09:21, Stefan Farfeleder wrote:
>>> On Sun, Nov 13, 2011 at 04:18:48PM +0000, David Chisnall wrote:
>>>> Author: theraven
>>>> Date: Sun Nov 13 16:18:48 2011
>>>> New Revision: 227487
>>>> URL: http://svn.freebsd.org/changeset/base/227487
>>>> 
>>>> Log:
>>>>  The spec says that FILE must be defined in wchar.h, but it wasn't.  It
>>>>  is now.  Also hide some macros in C++ mode that will break C++
>>>>  namespaced calls.
>>>> 
>>>>  Approved by:	dim (mentor)
>>> 
>>> I think this change is wrong. Whic spec are you referring to? C99
>>> defines FILE only in 7.19.1#2 (stdio.h). In other headers FILE is used
>>> as parameter type for functions but that does not mean it is exported to
>>> user space.
>> 
>> http://pubs.opengroup.org/onlinepubs/007908799/xsh/wchar.h.html
> 
> It's a niggling detail, but that's an extension to the C standard,
> so properly speaking, it belongs in an
>  #if __POSIX_VISIBLE >= 200809 || XSI_VISIBLE
> (or something like that).  The formals were struct __sFILE *
> instead of FILE * for that reason -- see r103177.
> 
> P.S. You're looking at a very old version of POSIX.  Check out:
>     http://pubs.opengroup.org/onlinepubs/9699919799/

The C99 and C1x specifications both seem to require stdio.h to be included before wchar.h.  I think this therefore places including wchar.h and not stdio.h in the category of undefined (or, at least, not defined) behaviour, so we are free to do anything in this case.  I would say that accepting the code and working as the programmer expected is the least harmful thing to do here.  This is what Darwin libc does (actually, it #includes stdio.h in wchar.h).  

David