Re: So You Think You Can Const?

Andrey Tarasevich <andreytarasevich@hotmail.com> writes:

On 01/07/25 11:32 AM, Julio Di Egidio wrote:

To the question, I was reading this, but I am not
sure what the quoted passage means:
Matt Stancliff, "So You Think You Can Const?",
<https://matt.sh/sytycc>
<< Your compiler, at its discretion, may also choose
    to place any const declarations in read-only storage,
    so if you attempt to hack around the const blocks,
    you could get undefined behavior. >>

>
Strictly speaking, the passage is misleading. It dues not matter
whether the compiler decided to place const data into read-only
storage. If you "hack around" data constness (i.e. if you attempt to
modify const data), you _always_ get undefined behavior, regardless of
where the data is actually stored.

And one possible result of undefined behavior (in some sense perhaps
the worst) is that the code behaves just as you expected it to.

The author of the article likely thought of "undefined behavior" as
"the program crashes" or "something goes terribly wrong".  In fact
undefined behavior is simply behavior that is not defined; the C
standard says nothing about what happens.

And if the manifestation of that undefined behavior is that the
code quietly does what you thought it would do, it could mean that
you have a latent bug that's difficult to track down, and that will
come back and bite you later.

[...]

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */