GNU bug report logs - #40671
[DOC] modify literal objects

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Dmitry Gutov <dgutov <at> yandex.ru>, Mattias Engdegård <mattiase <at> acm.org>, Richard Stallman <rms <at> gnu.org>
Cc: Michael Heerdegen <michael_heerdegen <at> web.de>, ke.vigouroux <at> laposte.net, 40671 <at> debbugs.gnu.org
Subject: bug#40671: [DOC] modify literal objects
Date: Sat, 25 Apr 2020 20:49:27 -0700

On 4/25/20 12:30 PM, Dmitry Gutov wrote:
> On 25.04.2020 06:20, Paul Eggert wrote:
>>> When a value is constant in C or C++, you can't change it.
>> Yes, you can't change it in a portable program, because if you attempt to change
>> it the resulting behavior is undefined. The attempt might succeed so that the
>> "constant" is changed, or you might get a core dump, or you might get an
>> exception, or something else might happen.
> 
> Might succeed? Will it even compile?

Yes, although the C/C++ program must type-check and satisfy all other static
constraints of course (otherwise it won't compile). Here's a simple example:

#include <string.h>
int main (void) { return !strcpy ("a", "b"); }

This function attempts to modify the "a" string constant, so it might dump core,
or might return 0, or might do other things.

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