Re: Detect Autoconf run in preprocessor?

[Jeffrey Walton]

On Fri, Jul 15, 2016 at 2:56 PM, Eric Blake <address@hidden> wrote:
> On 07/15/2016 12:47 PM, Jeffrey Walton wrote:
>> On Fri, Jul 15, 2016 at 2:35 PM, Bob Friesenhahn
>> <address@hidden> wrote:
>>> On Fri, 15 Jul 2016, Jeffrey Walton wrote:
>>>>
>>>>
>>>> Is there a preprocessor macro defined by Autotools to detect when
>>>> software is being configured by the tool? My apologies for asking; I
>>>> cannot simply run `g++ -dM -E - </dev/null` because it will lack
>>>> Autoconf specific defines.
>>>
>>>
>>> Everything that Autoconf defines should be visible in the generated
>>> config.log file.  The source for each test case is included.
>>
>> Thanks. I'll have to ask the person for it.
>>
>> But getting back to Autoconf defines, is there a preprocessor define
>> that Autoconf uses to identify itself?
>
> Autoconf does not define anything specific. You can write an early
> AC_DEFINE in your configure.ac to trigger a specific witness used in all
> subsequent probes, but that's a per-package solution.

Perfect, thanks.

Can the Autoconf folks recommend a name for the define? Maybe
something like GNU_AUTOCONF or similar?

The reason I ask: whatever name is recommended, I'm going to
re-recommend it to ensure consistency and to avoid 1-off solutions.
I'm also going to cite this thread as authority to use it in a
remediation.

Jeff