Crash on kiui_example startup about kiui HOT 12 CLOSED

Cannot reproduce. My best guess is that one of the data files hasn't been updated in your data install folder (from the last commits)

from kiui.

I have the same problem with the latest master. I'm getting a segfault with the following backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7a082cb in mk::Dockbar::vappend (this=0x91c740, widget=std::unique_ptr<mk::Widget> containing 0x0) at /home/users/morozov/Projects/U
pstream/kiui/src/Ui/Scheme/mkDockbar.cpp:57
(gdb) back
#0  0x00007ffff7a082cb in mk::Dockbar::vappend (this=0x91c740, widget=std::unique_ptr<mk::Widget> containing 0x0) at /home/users/morozov/Projec
ts/Upstream/kiui/src/Ui/Scheme/mkDockbar.cpp:57
#1  0x00007ffff7ab8f6e in mk::Sheet::emplace<mk::StyleEdit, mk::Styler&> (this=0x91c740) at /home/users/morozov/Projects/Upstream/kiui/src/Ui/W
idget/mkSheet.h:54
#2  0x00007ffff7aac6f0 in mk::createUiStyleEdit (parent=...) at /home/users/morozov/Projects/Upstream/kiui/src/Ui/mkUiExample.cpp:520
#3  0x00007ffff7aace8e in mk::createUiTest (root=...) at /home/users/morozov/Projects/Upstream/kiui/src/Ui/mkUiExample.cpp:593
#4  0x000000000041e5d2 in main (argc=1, argv=0x7fffffffe488) at /home/users/morozov/Projects/Upstream/kiui/example/example.cpp:36
(gdb) up
#1  0x00007ffff7ab8f6e in mk::Sheet::emplace<mk::StyleEdit, mk::Styler&> (this=0x91c740) at /home/users/morozov/Projects/Upstream/kiui/src/Ui/W
idget/mkSheet.h:54
(gdb) down
#0  0x00007ffff7a082cb in mk::Dockbar::vappend (this=0x91c740, widget=std::unique_ptr<mk::Widget> containing 0x0) at /home/users/morozov/Projec
ts/Upstream/kiui/src/Ui/Scheme/mkDockbar.cpp:57

from kiui.

Exactly same bt on very fresh installation of debian 9
Vote up. It's a blocker on Linux.

from kiui.

I'll investigate, but if someone on the system where it fails, can step the debugger to find a plausible origin, it's welcome.

from kiui.

The problem turns out to be very simple. std::move() in that last line (mkDockbar.cpp:57) destroys the contents of the widget unique_ptr. When it tries to call widget->name(), things break. The fix, of course, is trivial:

        auto name = widget->name();
        return this->addDock(name, icon, std::move(widget));

from kiui.

auto name = widget->name();

Not resolves problem. Because signature of this function:

const string &Widget::name()

which in this case returns reference to temporary and leads to segfault

See fix in a pull request #28
Please, merge
Regards, Alexey Knyshev

from kiui.

That's strange. Not only do I not see the second segfault, but the way I understand auto type deduction, in

auto name = widget->name();

auto gets resolved to string and one simply gets a local copy.

from kiui.

auto is resolved into direct return type which in this case in

const string &

And it is reference to string object in widget, so then it is going to be destroyed when widget is destroyed.

from kiui.

I really don't think that's how auto type deduction works. Here's a simple test for you, compile and try for yourself.

#include <type_traits>

struct A
{
    struct B {};
    const B& f () { return b; }
    B b;
};

int main()
{
    A a;
    auto x = a.f();
    static_assert(std::is_same<decltype(x), A::B>::value,        "A::B");
    static_assert(std::is_same<decltype(x), const A::B&>::value, "const A::B&");
}

Also worth noting, widget doesn't get destroyed anywhere in this function; a unique_ptr to it simply gets moved. So even if name was a const-reference, nothing would break — the addresses don't change.

from kiui.

Sorry, was asleep while writting comment about auto. Everything is ok with:

auto name = widget->name()

Regrads, Alexey Knyshev

from kiui.

BTW, my pull request is ok and may be merged 😄

from kiui.

Aaah yeah, the order isn't guaranteed to be ->name before std::move. Makes a lot of sense. Thanks for finding it while I'm away from computer.

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