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Date: Fri, 29 Aug 2014 12:12:00 -0000
From: Segher Boessenkool <segher@kernel.crashing.org>
To: =?utf-8?Q?J=C4=99drzej?= Dudkiewicz <jedrzej.dudkiewicz@gmail.com>
Cc: Jonathan Wakely <jwakely.gcc@gmail.com>,        Michael Williamson <michael.h.williamson@gmail.com>,        gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: odd behavior
Message-ID: <20140829121201.GA4468@gate.crashing.org>
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[Please don't top-post.  Thanks.]

> > #if 0
> > const char* s = ";
> > #endif
> > int main() { }

> Ah-ha! You're right. Now I see that this warning is issued by
> preprocessor, not by compiler. Now that I think about it, it seems
> logical. Preprocessor has to tokenize input to perform substitutions
> and such, so even if code isn't meant for compiler, it must follow
> some rules - ifdefined parts of code are not comments. Is that right?

C11 6.4/3 says the lonely quote is undefined behaviour.  Your program
might or might not work (the same) with a different (version of the)
compiler.  So a warning is good.


Segher