On Mon, Nov 16, 2020 at 09:24:22AM +0000, Daniel P. Berrangé wrote:
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@xxxxxxxxxx> --- 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 popI 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.
Even when the warning we're disabling actually catches errors we make every now
and then? Really?
I know the issue is very old and it only showed up now. And that the MR might
not go through for quite some time. But how about a middle ground like the one
I described in reply to Pavel? Looks like this:
#define G_DEFINE_TYPE_WITH_WORKAROUND(a, b, c) \
_Pragma ("clang diagnostic push") \
_Pragma ("clang diagnostic ignored \"-Wincompatible-pointer-types-discards-qualifiers\"") \
G_DEFINE_TYPE(a, b, c) \
_Pragma ("clang diagnostic pop")
If someone wants to make sure it does not break and we really want to get rid of
this ASAP, then we can even syntax-check for it, describe it and only use it
with glib that has this issue.
Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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