ColorSelector and showSliders crashes


Same code works perfectly for OS X and Windows.  But on Linux the ColorSelector crashes every time if I have 'showSliders' set in the options.  The other options don't make it crash.

This is on Mint17 64bit 


If you're going to make a "it crashed!" post, please always include a stack trace!


I don't build the JUCE libs with debug info, usually.  But here goes:

Program received signal SIGSEGV, Segmentation fault.

0x00007ffff69f5f31 in ?? () from /usr/lib/x86_64-linux-gnu/

(gdb) bt

#0  0x00007ffff69f5f31 in ?? () from /usr/lib/x86_64-linux-gnu/

#1  0x00007ffff69fc424 in std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, char, double) const ()

   from /usr/lib/x86_64-linux-gnu/

#2  0x00007ffff69fc710 in std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const () from /usr/lib/x86_64-linux-gnu/

#3  0x00007ffff6a07ca5 in std::ostream& std::ostream::_M_insert<double>(double) () from /usr/lib/x86_64-linux-gnu/

#4  0x0000000000472530 in juce::NumberToStringConverters::StackArrayStream::writeDouble (this=0x7fffffffdde8, n=0, numDecPlaces=7)

    at ../../JuceLibraryCode/modules/juce_core/text/juce_String.cpp:459

#5  0x000000000042dd3c in juce::NumberToStringConverters::doubleToString (buffer=0x7fffffffde78 "\250\336\377\377\377\177", numChars=48, n=0, numDecPlaces=7, 

    len=@0x7fffffffde68: 140737488346824) at ../../JuceLibraryCode/modules/juce_core/text/juce_String.cpp:494

#6  0x000000000042dde6 in juce::NumberToStringConverters::createFromDouble (number=0, numberOfDecimalPlaces=7)

    at ../../JuceLibraryCode/modules/juce_core/text/juce_String.cpp:512

#7  0x000000000042dfbc in juce::String::String (this=0x7fffffffdf28, number=0, numberOfDecimalPlaces=7)

    at ../../JuceLibraryCode/modules/juce_core/text/juce_String.cpp:528

#8  0x00000000005104b9 in juce::Slider::getTextFromValue (this=0x210c0e0, v=0) at ../../JuceLibraryCode/modules/juce_gui_basics/widgets/juce_Slider.cpp:1524

#9  0x000000000055a624 in juce::Slider::Pimpl::lookAndFeelChanged (this=0x20d8000, lf=...)

    at ../../JuceLibraryCode/modules/juce_gui_basics/widgets/juce_Slider.cpp:562

#10 0x000000000050ff9d in juce::Slider::lookAndFeelChanged (this=0x210c0e0) at ../../JuceLibraryCode/modules/juce_gui_basics/widgets/juce_Slider.cpp:1452

#11 0x000000000050f7ca in juce::Slider::init (this=0x210c0e0, style=juce::Slider::LinearHorizontal, textBoxPos=juce::Slider::TextBoxLeft)

    at ../../JuceLibraryCode/modules/juce_gui_basics/widgets/juce_Slider.cpp:1362

#12 0x000000000050f63f in juce::Slider::Slider (this=0x210c0e0, name=...) at ../../JuceLibraryCode/modules/juce_gui_basics/widgets/juce_Slider.cpp:1347

#13 0x0000000000731716 in juce::ColourSelector::ColourComponentSlider::ColourComponentSlider (this=0x210c0e0, name=...)

    at ../../JuceLibraryCode/modules/juce_gui_extra/misc/juce_ColourSelector.cpp:29

#14 0x000000000072b473 in juce::ColourSelector::ColourSelector (this=0x2118820, sectionsToShow=15, edge=4, gapAroundColourSpaceComponent=7)

    at ../../JuceLibraryCode/modules/juce_gui_extra/misc/juce_ColourSelector.cpp:322

#15 0x0000000000718241 in MyColourSelector::MyColourSelector (this=0x2118820, g=0x2090490, myflags=15, myedgeGap=4, gapAroundColourSpaceComponent=7)

    at src/juce_colour.cpp:17




Something looks pretty screwed up there.. Where is the rest of the stack trace showing the place that's actually creating the new MyColourSelector object?


The rest was just in my own code, I don't expect there's anything interesting there.


It's not being invoked from a static constructor, is it?


No, the code is:

gui->handle = new MyColourSelector(gui, 
#ifdef LINUX
                    10  // crash if we set it to 15... or -1
                    ,4, 7); 

The MyColourSelector ctor does the usual dance:

MyColourSelector::MyColourSelector(gui_t *g, int myflags, int myedgeGap, int gapAroundColourSpaceComponent) :
    ColourSelector(myflags, myedgeGap, gapAroundColourSpaceComponent) ,

And its declaration is likewise unremarkable:

class MyColourSelector : public ColourSelector, public ChangeListener


Since it's crashing in the String (double) constructor, have you tried just adding a line of code that does e.g. "String (123.0)" and seeing whether that also crashes? If it does still crash deep inside the C++ standard library like in your stack trace above, it's most likely that you've got some kind of weird compiler/std-library linkage  mismatch rather than this being related to any juce code.



That didn't make a difference.  Interestingly, the 32-bit linux build works fine, so it may be something to do with compilation flags 


Turns out it's not compiler flags.  Its the #$@# compiler.

N.B.: don't use gcc 4.8 on linux.  Or for that matter, gcc on any 64-bit intel platform.  It generates *bad* code.

What do I mean by "bad"?  It doesn't take precautions to ensure the stack (RSP) is correctly aligned.  And then it uses the xmm registers with *alignment required* instructions, so you get *random* crashes which depend on ... who knows what?

When I switched to 'clang-3.5' on Linux, this crash (and another one which is ultimately for the same reason) went away.  But not until I lost even more hair.