[libvirt PATCH] Do not disable incompatible-pointer-types-discards-qualifiers

[Daniel P. Berrangé]

On Sun, Nov 15, 2020 at 09:42:40PM +0100, Martin Kletzander wrote:
> This reverts commit b3710e9a2af402a2b620de570b062294e11190eb.
> 
> That check is very valuable for our code, but it causes issue with glib >=
> 2.67.0 when building with clang.
> 
> The reason is a combination of two commits in glib, firstly fdda405b6b1b which
> adds a g_atomic_pointer_{set,get} variants that enforce stricter type
> checking (by removing an extra cast) for compilers that support __typeof__, and
> commit dce24dc4492d which effectively enabled the new variant of glib's atomic
> code for clang.  This will not be necessary when glib's issue #600 [0] (8 years
> old) is fixed.  Thankfully, MR #1719 [1], which is supposed to deal with this
> issue was opened 3 weeks ago, so there is a slight sliver of hope.
> 
> [0] https://gitlab.gnome.org/GNOME/glib/-/issues/600
> [1] https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1719
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  meson.build               | 3 ---
>  src/qemu/qemu_domain.c    | 7 +++++++
>  src/util/vireventthread.c | 6 ++++++
>  src/util/viridentity.c    | 6 ++++++
>  src/util/virobject.c      | 6 ++++++
>  5 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/meson.build b/meson.build
> index cecaad199d4c..04646e3a078c 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -405,9 +405,6 @@ cc_flags += [
>    # so use this Clang-specific arg to keep it quiet
>    '-Wno-typedef-redefinition',
>  
> -  # Clang complains about casts in G_DEFINE_TYPE(...)
> -  '-Wno-incompatible-pointer-types-discards-qualifiers',
> -
>    # We don't use -Wc++-compat so we have to enable it explicitly
>    '-Wjump-misses-init',
>  
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 2158080a56ad..3349476cceae 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -330,7 +330,14 @@ struct _qemuDomainLogContext {
>      virLogManagerPtr manager;
>  };
>  
> +#pragma clang diagnostic push
> +/* Workaround for glib's issue #600 on clang */
> +#pragma clang diagnostic ignored "-Wincompatible-pointer-types-discards-qualifiers"
> +
>  G_DEFINE_TYPE(qemuDomainLogContext, qemu_domain_log_context, G_TYPE_OBJECT);
> +
> +#pragma clang diagnostic pop

I really don't want to see this pattern used. We may only have a handful
of G_DEFINE_TYPE today, but as we convert all 200  virClass over to GObject
this is going to be way to tedious.  This has to be done as a global
thing IMHO.


Regards,
Daniel
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