From: Xi Ruoyao <xry111@mengyan1223.wang>
To: Jonny Grant <jg@jguk.org>, gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: gcc warn when pointers not checked non-null before de-referencing.
Date: Wed, 16 Jun 2021 21:36:38 +0800 [thread overview]
Message-ID: <4dd0f2168668d9d3dd919df6088d0dea4cfe0bb5.camel@mengyan1223.wang> (raw)
In-Reply-To: <0770e060-6388-fc27-1178-205b867bfae2@jguk.org>
On Wed, 2021-06-16 at 14:01 +0100, Jonny Grant wrote:
> Chris Latner also mentioned integer overflow being undefined, that
> crops up too. There's no easy solution right, we need to hand write
> code the checks? It's human-error prone if we need to manually code
> each check. throwing in C++, or handling in C.
>
> if(N >= INT_MAX)
> {
> throw std::overflow_error("N >= INT_MAX would overflow in for
> loop");
> }
>
> for (i = 0; i <= N; ++i)
> {
> // ...
> }
For debugging use -fsanitize=undefined.
And this is buggy anyway, no matter if there is an UB:
for (unsigned i = 0; i <= N; i++)
make_some_side_effect_without_any_undefined_behavior(i);
If N may be UINT_MAX, this is not UB, but a dead loop. Programming is
just human-error prone, even if you use "some programming language
claimed to be able to eliminate many human errors" (I'll not say its
name, to prevent a flame war).
--
Xi Ruoyao <xry111@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2021-06-16 13:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-13 22:30 Jonny Grant
2021-06-14 5:15 ` Xi Ruoyao
2021-06-16 13:01 ` Jonny Grant
2021-06-16 13:36 ` Xi Ruoyao [this message]
2021-07-03 15:36 ` Jonny Grant
2021-07-06 15:39 ` Xi Ruoyao
2021-07-19 18:20 ` Jonny Grant
2021-06-16 17:59 ` Segher Boessenkool
2021-06-17 20:44 ` Jonny Grant
2021-06-18 4:16 ` Xi Ruoyao
2021-07-03 14:14 ` Jonny Grant
2021-07-03 16:22 ` Segher Boessenkool
2021-07-06 10:33 ` Jonny Grant
2021-06-18 8:38 ` Liu Hao
2021-06-18 14:53 ` Segher Boessenkool
2021-06-14 15:19 ` Martin Sebor
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