Re: [Qemu-devel] [PATCH] configure: Disable (clang) initializer-overrides warnings

[Blue Swirl]

On Sun, Oct 14, 2012 at 8:00 PM, Peter Maydell <address@hidden> wrote:
> Disable clang's initializer-overrides warnings, as QEMU makes significant
> use of the pattern of initializing an array with a range-based default
> entry like
>     [0 ... 0x1ff] = { GPIO_NONE, 0 }
> followed by specific entries which override that default, and clang
> would otherwise warn "initializer overrides prior initialization of
> this subobject" when it encountered the specific entry.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> This is basically a judgement that our coding style is legitimate
> and the compiler is being overly alarmist. I don't think we would
> benefit from trying to silence the warnings and I can't think of
> a clean way of doing so...
>
> NB that gcc will happily ignore -Wno-wombat warnings that it doesn't
> happen to recognize. (For compilers that don't accept-and-ignore the flag
> configure will identify this and not use it.)
>
> Blue Swirl previously submitted a patch which enabled this flag
> (among others):
> http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg04203.html

In my version, Clang flags were separate from GCC flags. I think it
would be better to run different tests for each compiler in the
future, that lets GCC avoid Clang flag -ffoobar which does not have
desirable effect to GCC and vice versa. I'd also like to handle flags
for sparse checker the same way.

>
> I haven't found the other two flags in that patch to be required.
>
>  configure | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/configure b/configure
> index 353d788..f78cfc5 100755
> --- a/configure
> +++ b/configure
> @@ -1187,6 +1187,7 @@ gcc_flags="-Wold-style-declaration 
> -Wold-style-definition -Wtype-limits"
>  gcc_flags="-Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers 
> $gcc_flags"
>  gcc_flags="-Wmissing-include-dirs -Wempty-body -Wnested-externs $gcc_flags"
>  gcc_flags="-fstack-protector-all -Wendif-labels $gcc_flags"
> +gcc_flags="-Wno-initializer-overrides $gcc_flags"
>  # Note that we do not add -Werror to gcc_flags here, because that would
>  # enable it for all configure tests. If a configure test failed due
>  # to -Werror this would just silently disable some features,
> --
> 1.7.11.4
>