On Tue, Sep 27, 2022 at 04:42:00PM +0200, Laszlo Ersek wrote:
> On 09/26/22 10:50, Daniel P. Berrangé wrote:
> > On Mon, Sep 26, 2022 at 10:18:06AM +0200, Laszlo Ersek wrote:
> >> gcc reports:
> >>
> >>> gui.c:1795:3: error: missing initializer for field ‘padding’ of
> >>> ‘GActionEntry’ {aka ‘const struct _GActionEntry’}
> >>> [-Werror=missing-field-initializers]
> >>> 1795 | { "shutdown", activate_action, NULL, NULL, NULL },
> >>>
> >>> gui.c:1796:3: error: missing initializer for field ‘padding’ of
> >>> ‘GActionEntry’ {aka ‘const struct _GActionEntry’}
> >>> [-Werror=missing-field-initializers]
> >>> 1796 | { "reboot", activate_action, NULL, NULL, NULL },
> >>
> >> I've found this only now because:
> >>
> >> - this is the first time I'm building virt-p2v with GTK3,
> >>
> >> - the "shutdown_actions" array depends on USE_POPOVERS which depends on
> >> GTK3 being selected,
> >>
> >> - the "missing-field-initializers" warning (treated as an error) has
> >> recently been enabled via "-Wextra" in commit 391f9833d398 ("p2v-c.m4:
> >> elicit a stricter set of warnings from gcc", 2022-09-23).
> >>
> >> The C-language documentation for GActionEntry is silent on the "padding"
> >> array:
> >>
> >> https://docs.gtk.org/gio/struct.ActionEntry.html
> >>
> >> However, the D-language docs expose it:
> >>
> >> https://api.gtkd.org/gio.c.types.GActionEntry.html
> >>
> >> Provide the missing field initializer.
> >>
> >> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> >> ---
> >> gui.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/gui.c b/gui.c
> >> index 49301d9a985b..4faaa710ed90 100644
> >> --- a/gui.c
> >> +++ b/gui.c
> >> @@ -1792,8 +1792,8 @@ static gboolean close_running_dialog (GtkWidget *w,
> >> GdkEvent *event, gpointer da
> >>
> >> #ifdef USE_POPOVERS
> >> static const GActionEntry shutdown_actions[] = {
> >> - { "shutdown", activate_action, NULL, NULL, NULL },
> >> - { "reboot", activate_action, NULL, NULL, NULL },
> >> + { "shutdown", activate_action, NULL, NULL, NULL, { 0 } },
> >> + { "reboot", activate_action, NULL, NULL, NULL, { 0 } },
> >> };
> >
> > Notice the header decl says 'padding' is private hence why it is
> > not documented.
> >
> > struct _GActionEntry
> > {
> > const gchar *name;
> >
> > void (* activate) (GSimpleAction *action,
> > GVariant *parameter,
> > gpointer user_data);
> >
> > const gchar *parameter_type;
> >
> > const gchar *state;
> >
> > void (* change_state) (GSimpleAction *action,
> > GVariant *value,
> > gpointer user_data);
> >
> > /*< private >*/
> > gsize padding[3];
> > };
> >
> >
> > The purpose of this 'padding' entry is to reserve space in the struct
> > for future usage. Apps should never touch the padding field, since it
> > can change in future. ie that 3 element array can turn into three
> > separate public fields later, and then the compound initializer above
> > would be invalid.
>
> Right; I thought we'd just fix it again at that point :)
>
> >
> > The right way to declare this is using named initializers:
> >
> > { .name = "shutdown", .activate = activate_action },
> > { .name = "reboot", .activate = activate_action },
>
> I wasn't sure if the p2v coding style permitted designated
> initializers... Now that I'm looking closer, yes, there is "prior art";
> in compound literals in "ssh.c".
As the most prolific recent contributor the coding style is roughly
whatever you say at this point :-)
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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