1728532 - GLib-GObject-CRITICAL assertion failure when opening the Print dialog

Status: RESOLVED INCOMPLETE

(Core :: Widget: Gtk, defect)

Description

[Valentin Villenave]

Attachment: thunderbird_print_dialog_bt.txt

When opening the Print dialog in any message or compose window,
I’m getting the following warning:

Critical(thunderbird:2243): GLib-GObject-CRITICAL **: g_object_ref: assertion 'G_IS_OBJECT (object)' failed

When launched with --g-fatal-warnings, this causes the program
to crash and to open the Crash Reporter.

This has been happening ever since the new Print dialog was added, AFAICS.

Attached is a gdb backtrace.

Comment 1

[Magnus Melin [:mkmelin]]

Thunderbird just uses the platform code now. The warning is of not (to my knowledge) causing any problem.

Comment 2

[Martin Stránský [:stransky] (ni? me)]

Can it be here?
https://searchfox.org/mozilla-central/rev/a166f59fba89fc70ebfab287f4edb8e05ed4f6da/widget/gtk/nsPrintSettingsGTK.cpp#110

Is it possible that rhs.mGTKPrinter is nullptr?

It may mean there isn't any printer connected. Valentin, do you see any issues with the printing or just this message?

Comment 3

[Colomban Wendling]

Can it be here? https://searchfox.org/mozilla-central/rev/a166f59fba89fc70ebfab287f4edb8e05ed4f6da/widget/gtk/nsPrintSettingsGTK.cpp#110

Is it possible that rhs.mGTKPrinter is nullptr?

Sounds reasonable with the backtrace, and given how mGTKPrinter is being used all over this file (e.g. GTK_IS_PRINTER, and the fact it's only initialized to nullptr in the constructor) it does sounds like it could be.

Even if this wouldn't "seem" to cause much problem in normal usage (if you found the spot, it merely returns NULL from the assertion error), such a warning means an invalid object is being used which is a problem by itself. Also, although it's uncommon to see such builds, known that GObject, GTK & co can be built disabling those checks (e.g. for performance reasons), and in such builds it would merely crash (or worse) as the check would not happen and the invalid object would actually be used.

Comment 4

[Valentin Villenave]

Printing does works fine; I do have a major stumbling block with this
dialog as it doesn’t always correctly take the focus and therefore
isn’t correctly exposed to screen readers, but I’m not sure whether
that accessibility problem is related to the aforementioned GLib
assertion failure.

Comment 5

[Wayne Mery (:wsmwk)]

Does it still fail for you?

Comment 6

[BugBot [:suhaib / :marco/ :calixte]]

Redirect a needinfo that is pending on an inactive user to the triage owner.
:stransky, since the bug has recent activity, could you have a look please?

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