From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: noloader@gmail.com, bug-gnulib@gnu.org, Bruno Haible <bruno@clisp.org>
Subject: Re: warnings in unit tests
Date: Wed, 9 Jun 2021 16:35:41 +0300 [thread overview]
Message-ID: <20210609133541.GA28264@altlinux.org> (raw)
In-Reply-To: <948c6b04-883b-0385-0cd1-77be21b3becd@cs.ucla.edu>
On Tue, Jun 08, 2021 at 09:42:55AM -0700, Paul Eggert wrote:
> For what it's worth I'm more with Bruno on this. For the tests, the cost
> of these warnings outweighs the benefit.
>
> It'd be OK with me to disable the troublesome warnings globally for the
> tests subdirectory, using -Wno-missing-prototypes or whatever.
>
> For the -Wnull-dereference issue it may be worthwhile to use a
> circumlocution that fools GCC into not issuing the warning. After all, a
> compiler smart enough to warn about '*(volatile int *) 0 = 42' might
> also be smart enough to see that it's undefined behavior and therefore
> omit the assignment's effect entirely. Perhaps something like the
> attached (untested) patch?
> diff --git a/tests/test-sigsegv-catch-stackoverflow2.c b/tests/test-sigsegv-catch-stackoverflow2.c
> index b94d1310b..bfd4617a3 100644
> --- a/tests/test-sigsegv-catch-stackoverflow2.c
> +++ b/tests/test-sigsegv-catch-stackoverflow2.c
> @@ -50,6 +50,7 @@ sigset_t mainsigset;
>
> volatile int pass = 0;
> uintptr_t page;
> +int volatile *null_pointer_to_volatile;
>
> static void
> stackoverflow_handler_continuation (void *arg1, void *arg2, void *arg3)
> @@ -183,7 +184,7 @@ main ()
> *(volatile int *) (page + 0x678) = 42;
> break;
> case 3:
> - *(volatile int *) 0 = 42;
> + *null_pointer_to_volatile = 42;
> break;
> case 4:
> break;
Thanks, this patch works, I'd definitely prefer applying it rather than
disabling -Wnull-dereference.
--
ldv
next prev parent reply other threads:[~2021-06-09 13:35 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-16 17:01 new module 'sigsegv' Bruno Haible
2021-06-06 23:27 ` Dmitry V. Levin
2021-06-07 0:49 ` Bruno Haible
2021-06-07 10:29 ` Dmitry V. Levin
2021-06-08 1:45 ` Jim Meyering
2021-06-08 2:40 ` warnings in unit tests Bruno Haible
2021-06-08 5:55 ` Jim Meyering
2021-06-08 8:56 ` Bruno Haible
2021-06-09 0:41 ` Dmitry V. Levin
2021-06-10 20:05 ` Bruno Haible
[not found] ` <CAH8yC8kHTq5J9onJj+2jwy_DwzXrwujqFs9TEBxGh5k_KCu=kg@mail.gmail.com>
2021-06-08 10:57 ` Bruno Haible
2021-06-08 16:42 ` Paul Eggert
2021-06-09 13:35 ` Dmitry V. Levin [this message]
2021-06-09 19:38 ` Bruno Haible
2021-06-10 19:39 ` Bruno Haible
2021-06-09 7:23 ` Bernhard Voelker
2021-06-09 14:17 ` Bruno Haible
2021-06-10 8:13 ` Simon Josefsson via Gnulib discussion list
2021-06-10 19:51 ` Bruno Haible
2021-06-10 21:49 ` Simon Josefsson via Gnulib discussion list
2021-06-11 12:21 ` Eric Blake
2021-06-11 13:57 ` Bruno Haible
2021-06-19 12:02 ` new module 'sigsegv' Bruno Haible
2021-06-21 18:22 ` [PATCH] sigsegv, sigsegv-tests: Assign my contributions to the FSF Eric Blake
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