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Re: Turn off GTK+ warnings




On 01/04/17 20:24, Emmanuele Bassi wrote:
> On 1 April 2017 at 11:05, Stuart Longland <stuartl@xxxxxxxxxxxxxxxxxx> wrote:
>> On 01/04/17 17:41, Stefan Salewski wrote:
>>> On Sat, 2017-04-01 at 16:53 +1000, Stuart Longland wrote:
>>>> How, as a user, do I go about silencing these warnings?
> 
> - Doctor, doctor! My arm hurts when I move it this way!
> - Then don't move it this way
> 
> You're blaming the nervous system notifying you that you're doing
> something wrong and/or painful, and you're asking to ignore the pain,
> instead of figuring out the cause and fixing that.
> 
> The pain you feel is the message; you fix the cause, not the pain.

If my arm were sore, I'd see a doctor, I would not bother seeing a
police officer about it, at best they'll simply refer me to a doctor, at
worst they may choose to press charges on wasting police time.

GTK+ is complaining to me about its "sore arm" … it should really go see
the "doctor" (the application developer).

>>> I don't think it is a good idea to ignore such warnings as a user in
>>> general case. There may be very few warnings, for which it may be ok to
>>> ignore it. But generally, there is a reason why warnings are shown.
>>> Indicating that something is wrong, and the software may not work
>>> properly.
>>>
>>> I would very strong try to avoid software which continuesly emit
>>> warnings -- that may be an indication that the software is stale,
>>> nobody cares about it, so it may have dangerous (security) bugs.
>>>
>>> One example was indeed gvim, I have stopped using it.
>>
>> Well, in my case it isn't `gvim` that's emitting the warnings, its GTK+.
>>  `gvim`'s (ab)use of the GTK+ library might be the underlying cause, but
>> GTK+ is what's polluting stderr.
> 
> GTK+ is not "polluting" stderr: it's emitting a warning that the
> application is doing something wrong at run time. The application is
> causing the warning.

GTK+'s warning is polluting stderr.  stderr is meant for the application
to report things via the console, not GTK+.  GTK+ has permission to talk
to the X server, but not to stderr.

In the case of `gvim`, they don't think it's their problem:
https://github.com/vim/vim/issues/1149

I have a hunch it is theme-related.  I tried several before finally
settling on the vertex theme, which seemed to generate less errors than
others, including the default GTK+ theme.

That puts the ball firmly in GTK+'s court in my book.

> You should file a bug against the application that is creating those
> warnings.

I have, right here.  Those warnings are being emitted by GTK+.  This is
the GTK+ mailing list.

My proposal for a fix is that the warnings should be conditional on some
run-time flag which is enabled by GTK+ application developers.

Then developers can get all the warnings they want, even more detail
then they get now.

In a perfect world, the developer would be looking for and fixing those
issues.  As you can see from this email thread, and the above linked bug
report, we live in a real world, not a perfect one.

As mentioned, it isn't just `gvim` that's an offender here… this is from
my .xsession-errors:

> (gkrellm:4216): GLib-GObject-WARNING **: The property GtkWindow:allow-shrink is deprecated and shouldn't be used anymore. It will be removed in a future version.
> (nm-applet:4201): GLib-GObject-WARNING **: The property GtkButton:use-stock is deprecated and shouldn't be used anymore. It will be removed in a future version.
> (pasystray:4197): GLib-GObject-WARNING **: The property GtkButton:use-stock is deprecated and shouldn't be used anymore. It will be removed in a future version.
> (firefox:4256): GLib-GObject-WARNING **: The property GtkSettings:gtk-menu-images is deprecated and shouldn't be used anymore. It will be removed in a future version.
> (thunderbird:4259): Gtk-CRITICAL **: IA__gtk_clipboard_set_with_data: assertion 'targets != NULL' failed
> (gimp:12309): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",
> (gimp:12309): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",
> Gtk-Message: (for origin information, set GTK_DEBUG): failed to retrieve property `gtk-primary-button-warps-slider' of type `gboolean' from rc file value "((GString*) 0x558da0738da0)" of type `gboolean'

Some of those are Gnome projects.

> Of course, since some application authors simply don't care
> that their application is generating warnings (otherwise they'd have
> already fixed it) your bet as to what will happens next is as good as
> mine. As a toolkit developer I can only tell you that GTK+ won't stop
> emitting those warnings because that's how application developers
> identify and fix bugs in their code — and, sometimes, in GTK+ itself.

As I said before, I'm not saying getting rid of the warnings, I'm
saying, have a facility to turn them on and off at runtime and perhaps
re-direct them to a place where they may be more useful.

It does not need to be fancy.  A check for an environment variable at
start up initialising a uint8_t tucked away somewhere in GTK+'s bowels
would suffice; if non-zero, emit a warning, if zero, shut up.

>>> If you really need that software, you may contact its author or
>>> maintainers of your OS distribution, maybe it is a problem of the
>>> distribution, maybe they ship too old or incompatible libraries or are
>>> doing something just wrong.
>>
>> Well as it happens, I do need GTK+, and hence, I believe this is the
>> mailing list for the authors of GTK+. :-)
> 
> This is gtk-list; if you want to contact the GTK+ developers you
> should use gtk-devel-list@xxxxxxxxx.
> 
> We'll tell you the same thing I told you above, though: file a bug
> against the application that emits the warnings.

No problems, I'll track down the GTK+ bug tracker and file a bug
accordingly.

>>> So we should be happy that these warnings are shown at all, it would be
>>> much worse when they are invisible or do not exist at all and software
>>> just malfunctions in rare cases.
>>
>> I'm not saying to get rid of the warnings, to a developer, they are very
>> useful clues as to what might be wrong with an application.
> 
>> For me as a user, they are useless junk that is cluttering up my
>> terminal session, pushing data I actually *do* care about off the
>> scrollback buffer and making my life harder.
> 
> There's no way for an application, or a library, or any computer
> program really, to discern intent or context.

No, there isn't yet… so let's give it a mechanism for telling it what's
going on.

> Even if there was a way for you to provide context — an environment
> variable, a toggle to remove warnings — the underlying issue is that
> anything that comes after a critical warning inside GTK+ steps you
> into "undefined behaviour" territory. Your application may cease to
> work at any point, eat all your data, and turn you into a frog,
> waiting for the kiss of minor royalty to break the spell.

Yep, and in such cases, the debugging procedure can be something along
the lines of:

GTK_ENABLE_WARNINGS=1 ./mybuggyapp

… and try to reproduce the bug whilst looking at what the warning
messages are telling you.

Even better is:

GTK_ENABLE_WARNINGS=/path/to/logfile ./mybuggyapp

Then you've got a log you can email around.

> A "simple"
> warning is less severe, but generally points to a misuse of the GTK+
> API to the point of breaking internal assumptions — and it usually
> leads to a critical warning somewhere down the line, with all that it
> entails (crash, data loss, amphibian transfiguration).
> 
> You, as a user, have a single recourse: file a bug against the
> application that causes the warning.

I'm saying these warnings can be better handled, and should be better
handed.  It isn't rocket science; the following would suffice:

/* in GTK+ somewhere */
static uint8_t verbose_warnings = 0;
…
if (getenv("GTK_ENABLE_WARNINGS")) {
    verbose_warnings = 1;

…

if (verbose_warnings)
    fprintf(stderr, "(%s:%d): Gtk-WARNING **: Amphibious transmutation
in progress!!!\n", argv[0], getpid());

For full-time GTK+ (application) developers, GTK_ENABLE_WARNINGS can be
set in .profile.
-- 
Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...
  ...it's backed up on a tape somewhere.

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