Debugging a specific crash under Win 10

[Lubomir I. Ivanov]

On 9 April 2017 at 10:08, Stefan Fuchs <sfuchs at gmx.de> wrote:
> Hi All,
>
> still I try to learn how to debug Subsurface under Windows 10 but with very
> small progress. But now I have a good example where with some help I maybe
> could learn a little bit more.
>
> I have the following situation:
> - Subsurface MXE windows debug build based on current master plus a few
> modifications from my side
> - When entering some text in the notes field of a dive in a specific
> condition Subsurface freezes completely (can provide more detailed info on
> request!)
> - I now attach drmingw to the frozen Subsurface.exe, results see attached
>
> Questions:
> - Is drmingw the right choice for this or is there any better tool for me?

i haven't tried drmingw, but last time i've checked there are no
competitive alternatives to something as powerful as Valgrind which is
available on Linux.
given it's sounds like a specialized tool for mingw debugging then it
might be a good choice.

> - Can s.o. read s.th. from the output?
> - What is the interesting part? I guess this one:

this is called a stack trace. as a rule of thumb, you want to look for
the last call from the subsurface source code. this is it:

> 0041DF74 4F917810 03C7CC84 00000000  subsurface.exe!fromCursorTilWhitespace
> [/home/stefan/Entwicklung/Subsurface/subsurface/desktop-widgets/simplewidgets.cpp
> @ 761]

this is now part of the Qt source code:

> 0A52B6CB 03C7CC84 00000001 00000000  Qt5Guid.dll!selectedText
> [/home/stefan/Entwicklung/Subsurface/mxe-2016-10-12/tmp-qtbase-i686-w64-mingw32.shared/qtbase-opensource-src-5.7.0/src/gui/text/qtextcursor.cpp
> @ 1721]

but we may be doing something bad in Subsurface with our
fromCursorTilWhitespace()
and QTextCursor::selectedText() should not crash.

> - When entering some text in the notes field of a dive in a specific
> condition Subsurface freezes completely (can provide more detailed info on
> request!)

try to obtain the exact contents of the notes field when it crashes.

lubomir
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