Re: popen and pclose redefinitions causing many warning in Windows build

On 05/14/2014 08:15 AM, Heikki Linnakangas wrote:
> On 05/09/2014 02:56 AM, Noah Misch wrote:
>> On Thu, May 08, 2014 at 12:14:44PM -0400, Tom Lane wrote:
>>> Andrew Dunstan <andrew@dunslane.net> writes:
>>>> I'm pretty sure we need this on Mingw - this SYSTEMQUOTE stuff dates
>>>> back well before 8.3, IIRC, which is when we first got full MSVC 
>>>> support.
>>>
>>> I tried googling for some info on this, and got a number of hits
>>> suggesting that mingw didn't emulate popen at all till pretty recently.
>>> For instance this:
>>> https://lists.fedoraproject.org/pipermail/fedora-mingw/2009-September/002087.html 
>>>
>>> Jones is an ex-coworker of mine, and I'm pretty sure that if he said
>>> it wasn't there then it wasn't there.
>>
>> I doubt MinGW has overridden popen() at runtime; that would be 
>> contrary to its
>> design criteria.  The headers, however, are MinGW territory. MinGW 
>> declares
>> both _popen() and popen() as functions.  MinGW-w64, a project more 
>> distinct
>> from MinGW than it sounds, uses "#define popen _popen":
>>
>> MinGW: 
>> http://sourceforge.net/p/mingw/mingw-org-wsl/ci/master/tree/include/stdio.h#l467
>> MinGW-w64: 
>> http://sourceforge.net/p/mingw-w64/code/HEAD/tree/trunk/mingw-w64-headers/crt/stdio.h#l496
>>
>> Building with any recent MinGW-w64, 32-bit or 64-bit, gets the reported
>> warnings; building with MinGW proper does not.
>
> Hmm. The MinGW-w64 header does this:
>
>> #if !defined(NO_OLDNAMES) && !defined(popen)
>> #define popen _popen
>> #define pclose _pclose
>> #endif
>
> So if we defined popen() before including stdio.h, that would get rid 
> of the warning. But we don't usually do things in that order.
>
> Could we define NO_OLDNAMES? I couldn't find any documentation on it, 
> but it seems to a bunch of lot of wrapper functions and defines. If we 
> can get away without them, that seems like a good thing...
>
>


Why don't we simply undefine it if it's defined before we redefine it? 
We don't need or want their definition, as our implementation calls 
_popen directly.

cheers

andrew