GCC question

Carl Johnson carlj at peak.org
Sat Sep 5 16:10:31 UTC 2015

"William A. Mahaffey III" <wam at hiwaay.net> writes:

> On 09/05/15 09:13, andrew clarke wrote:
>> On Sat 2015-09-05 08:34:27 UTC-0453, William A. Mahaffey III (wam at hiwaay.net) wrote:
>>>> I have some code which was originally SGI native, then moved to Linux
>>> (FC14 x86_64 & CentOS 5). I am now interested in getting it going under
>>> FreeBSD 9.3R. Due to differences in system header file includes, I need
>>> to tweek some of my app-specific header files. I have poked around the
>>> (*COPIOUS* !!!!) GCC man page & I couldn't find (or missed) either how
>>> to get it to regurgitate its default compiler-defines or a tabulation of
>>> those defines, so I can use them to conditionally include system headers
>>> in my own header files. Where is this info :-) ? TIA & have a nice
>>> (long) weekend.
>> You probably want:
>> gcc -dM -E - < /dev/null
>> Ordinarily to detect FreeBSD you'd use:
>> #ifdef __FreeBSD__
>> ...
>> #endif
> *Booooyah* !!!! Both worked AOK. I haven't used gcc in a while, so
> there may be a few more noob-ish questions to follow :-/ .... Thanks
> again & have a nice weekend.

As long as this came up, does anybody know of a similar incantation to
show the defined rules and symbols for make?  I remember seeing
something like that years ago, but I haven't been able to find it


Carl Johnson		carlj at peak.org

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