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[wwwdocs] Suggest UBsan in https://gcc.gnu.org/bugs/

Message ID 20151006111626.GR12094@redhat.com
State New
Headers show

Commit Message

Jonathan Wakely Oct. 6, 2015, 11:16 a.m. UTC 
On 06/10/15 11:54 +0100, Jonathan Wakely wrote:
>For many non-bugs UBsan is at least as likely to reveal it as
>-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations so we
>should tell people to try that before wasting time in Bugzilla.
>
>OK for wwwdocs?

>Index: htdocs/bugs/index.html
>===================================================================
>RCS file: /cvs/gcc/wwwdocs/htdocs/bugs/index.html,v
>retrieving revision 1.116
>diff -u -r1.116 index.html
>--- htdocs/bugs/index.html	5 Jul 2014 21:52:32 -0000	1.116
>+++ htdocs/bugs/index.html	6 Oct 2015 10:50:32 -0000
>@@ -50,7 +50,11 @@
> with <code>gcc -Wall -Wextra</code> and see whether this shows anything
> wrong with your code.  Similarly, if compiling with
> <code>-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations</code>
>-makes a difference, your code probably is not correct.</p>
>+makes a difference, your code probably is not correct.
>+If compiling with <code>-fsanitize=undefined</code> is supported by your
>+version of GCC and produces any run-time errors your code is definitely
>+not correct.
>+</p>
> 
> <h2>Summarized bug reporting instructions</h2>
> 

On IRC Markus pointed out that ubsan works in all supported releases,
and that some code that gets ubsan errors still shows real gcc bugs,
so here's an updated patch.

Comments

Gerald Pfeifer Oct. 7, 2015, 2:18 p.m. UTC | #1 
On Tue, 6 Oct 2015, Jonathan Wakely wrote:
> On IRC Markus pointed out that ubsan works in all supported releases,
> and that some code that gets ubsan errors still shows real gcc bugs,
> so here's an updated patch.

This looks like a nice addition, thank you!

Gerald
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Patch

Index: htdocs/bugs/index.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/bugs/index.html,v
retrieving revision 1.116
diff -u -r1.116 index.html
--- htdocs/bugs/index.html	5 Jul 2014 21:52:32 -0000	1.116
+++ htdocs/bugs/index.html	6 Oct 2015 11:15:04 -0000
@@ -50,7 +50,9 @@ 
 with <code>gcc -Wall -Wextra</code> and see whether this shows anything
 wrong with your code.  Similarly, if compiling with
 <code>-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations</code>
-makes a difference, your code probably is not correct.</p>
+makes a difference, or if compiling with <code>-fsanitize=undefined</code>
+produces any run-time errors, then your code is probably not correct.
+</p>
 
 <h2>Summarized bug reporting instructions</h2>