gcc -dM -E -xc /dev/null & g++ -dM -E -xc /dev/null

Ross Smith rosss@pharos.co.nz
Mon Oct 13 22:14:00 GMT 2003


Rick Rankin wrote:
> --- Christopher Faylor <cgf-rcm@cygwin.com> wrote:
> 
>>On Mon, Oct 13, 2003 at 07:22:28AM +0200, Alex Vinokur wrote:
>>
>>>gcc -dM -E -xc /dev/null
>>> and
>>>g++ -dM -E -xc /dev/null
>>> produce the same output.
>>>
>>>Is this a feature or a bug?
>>
>>It is not a bug.  Try it on linux.
>>
>>
>>>How can one know that g++ (not gcc) is invoked?
>>
>>Isn't the __cplusplus define a feature of c++?  I'm too lazy to check if this
>>is a g++ extension but I'd be surprised if it was.
> 
> Yes, it's defined in section 16.8 (Predefined macro names) of the ANSI/ISO
> standard.

The original poster was using the -xc flag, which tells the compiler
that the following source file is to be read as C regardless of the
file name. I'd expect exactly the same preprocessor output from both
frontends in that case.

-- 
Ross Smith ...................... Pharos Systems, Auckland, New Zealand

     "I virtually never go out of the house with less computing
     power on my person than the entire North American continent
     circa 1973." -- Charlie Stross



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