Re: Strict aliasing problem with rte_eth_linkstatus_set()

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 10 Apr 2024 19:54:27 +0200
Morten Brørup <mb@smartsharesystems.com> wrote:

> > Please send a patch to replace alias with union.  
> 
> +1
> 
> Fixing this specific bug would be good.
> 
> Instinctively, I think we should build with -fno-strict-aliasing, so the compiler doesn't make the same mistake with similar code elsewhere in DPDK. I fear there is more than this instance.
> I also wonder if -Wstrict-aliasing could help us instead, if we don't want -fno-strict-aliasing.


Strict aliasing checks should be enabled already if you use warning_level 2
and default (debugoptimized) or release build types. Unless some part of DPDK
meson config is not overriding that.

  https://mesonbuild.com/Builtin-options.html

Warning level 2 sets -Wall and -Wextra
From gcc man page

       -Wstrict-aliasing
           This option is only active when -fstrict-aliasing  is  active.   It
           warns  about  code  that might break the strict aliasing rules that
           the compiler is using for optimization.  The warning does not catch
           all cases, but does attempt to catch the more common pitfalls.   It
           is included in -Wall.  It is equivalent to -Wstrict-aliasing=3

and
           The -fstrict-aliasing option is enabled at levels -O2, -O3, -Os.