Crash when exiting text edit mode

• Jan 19, 2015 - 17:21
Type
Functional
Severity
S2 - Critical
Status
closed
Project
MuseScore

Steps:
1- open My_first_Score;
2- double-click on title text "Title" to enter text edit mode;
3- click outside the text to exit text edit mode -> crash

Windows 8.1 and Linux Mint 17.1, commit 140a510
Attached gdb backtrace

Attachment Size
text_edit_crash.txt 4.54 KB

Comments

• Jan 19, 2015 - 18:22

Yes! I'm fight this all day now! How did you get the stack trace?
I only got
Fatal: ASSERT failure in QVector::operator[]: "index out of range", file C:/Qt/5.4/mingw491_32/include/QtCore/qvector.h, line 396 (:0, )
And an exit, no stack

It is happing every time you use a click somewhere to exit any edit mode (almost any? not on chord symbols apparently)

The top stack frame still in MuseScore code is:
qreal a = grip[0].width() * 1.0;
And there is a recent change, 16764d4, related to that
(and your 140a510 is a few commit younger)

Reply

• Jan 19, 2015 - 18:23

So, I'm betting there are no grips, so grip[0] is bogus. If so, and if it's OK that text elements have no grip (I guess that is something that changed with a recent commit), then surrounding this passage with "if (grips)" would solve the problem. But if the text element is suppsoed to have a grip, then I don't know where / how to make that change.

Reply

• Jan 19, 2015 - 18:35

Before the change to the grip code, "grips" was 0 also, so I think it's fine that text elements have no grip. it's just that previously, "grip" was a static array of size MAX_GRIPS, and now it is dynamically allocated. So indeed, that looks like the fix - just protect that whole section of code with "if (grips)".

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• Jan 20, 2015 - 11:06

Thanks for the quick fix!

@Jojo-Schmitz:
I obtained the stack trace with a "trick" :-)
I run mscore in gdb under Linux, because in cases like this one (qAssert) gdb doesn't give the full stack trace under Windows (probably the application has already exited at the qAssert).
I think that under Windows a full backtrace can be obtained by putting a breakpoint at qFatal or qAssert. See also http://www.qtcentre.org/threads/8306-Back-tracing-asserts-with-gdb

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