[lldb-dev] [Interest] Qt 5 Creator 3.3 (Mac) Debugger locks up with endless error logging of "DW_AT_specification(address) has no decl"

[Greg Clayton]

This happens when you parse DW_TAG_subprogram or DW_TAG_inlined_subroutine tags and they have DW_AT_specification or DW_AT_abstract_origin attributes that point to where the function was defined (its declaration context (which classes and namespaces it was in)) and we try to go and figure out the decl context for a type and we get nothing in response. 

You can send me one of the .o files that are mentioned in the warning along with the warning that is emitted? Don't send it to the list, just send it to me with the appropriate message and I can look at the DWARF and see what is going on.

Greg Clayton


> On Feb 3, 2015, at 6:10 AM, René J.V. Bertin <rjvbertin at gmail.com> wrote:
> 
> Hello,
> 
> I'm forwarding a message sent to the Qt interest ML yesterday, because it concerns an issue I've encountered as well. For me, it occurred when stepping over a badly chosen expression like (from KDE4's Solid libs):
> 
>            const int index = iface->metaObject()->indexOfProperty(d->property.toLatin1());
>            QMetaProperty metaProp = iface->metaObject()->property(index);
>            QVariant value = metaProp.isReadable() ? metaProp.read(iface) : QVariant();
>            QVariant expected = d->value;
> 
> It looks like a combination of an lldb issue that's aggravated by the fact Qt Creator uses Python to control lldb. I have however been able to get out of the situation by repeating "Abort Debugging" twice, and a killall -9 of the app I was debugging.
> 
> What's going on here? I presume the OP uses Apple's current LLVM tool chain, like I do.
> 
> René.
> 
> ----------  Forwarded Message  ----------
> 
> Subject: [Interest] Qt 5 Creator 3.3 (Mac) Debugger locks up with endless error logging of "DW_AT_specification(address) has no decl"
> Date: Monday February 02 2015, 15:11:48
> From: <X at wavemetrics.com>
> To: interest at qt-project.org
> 
> I'm hoping someone can tell me how we can fix our Qt development environment to avoid this frustration:
> 
> Way too often Qt Creator 3.3 completely locks up when it hits certain breakpoints in our app using our self-compiled Qt 5.4.1 on Mac OS X 10.9.5.
> 
> (It is not clear what causes some breakpoints to lock up when most other breakpoint pose no problem.)
> 
> This is a problem we've had with earlier combinations of Qt, Qt Creator and Mac OS X.
> 
> When the Qt Creator Debugger UI locks up, stepping or resuming execution are not possible, and the Debugger Log very slowly writes hundreds of errors and warnings about "DW_AT_specification(address) has no decl".
> 
> Once this begins, there is no way to recover a working debugging session short of a computer reboot or laborious process-ID genocide.
> 
> ------- Debugger Log Example Extract ---------
> ...
> warning: (x86_64) /Source/IgorDev7/Igorsrc7/build-IgorPhoenix-64_bit_Qt_5_from_SVN-Debug/debug/IgorWindowUtilities.o 0x2a0009ac67: DW_AT_specification(0x000767fb) has no decl
> 
> ERROR: Lldb stderr: warning: (x86_64) /Source/IgorDev7/Igorsrc7/build-IgorPhoenix-64_bit_Qt_5_from_SVN-Debug/debug/wDataClassForEmbeddedQWidget.o 0x2b0009c964: DW_AT_specification(0x0007c91e) has no decl
> 
> ERROR: Lldb stderr: warning: (x86_64) /Source/IgorDev7/Igorsrc7/build-IgorPhoenix-64_bit_Qt_5_from_SVN-Debug/debug/CurveFittingDialog.o 0x6c000ba7f1: DW_AT_specification(0x00013bc0) has no decl
> 
> ERROR: Lldb stderr: warning: (x86_64) /Source/IgorDev7/Igorsrc7/build-IgorPhoenix-64_bit_Qt_5_from_SVN-Debug/debug/CurveFittingDialog.o 0x6c000ba84f: DW_AT_specification(0x00013c42) has no decl
> 
> warning: (x86_64) /Source/IgorDev7/Igorsrc7/build-IgorPhoenix-64_bit_Qt_5_from_SVN-Debug/debug/CurveFittingDialog.o 0x6c000ba9fa: DW_AT_specification(0x00013cbc) has no decl
> ...
> --------------------------
> 
> Our Qt 5.4.1 has been compiled using a command like:
> 
> echo yes | MAKEFLAGS=-j16 QMAKESPEC=/qtbuild/qt/mkspecs/unsupported/macx-clang  ../../qt/configure -debug-and-release -opensource -no-qt3support -nomake examples -nomake demos -nomake tests -silent -no-sql-mysql -no-webkit -cocoa -arch x86_64 -arch x86 -no-phonon -no-phonon-backend -prefix /qtbuild/install/macosx
> 
> --Jim
> 
> ===============================================
> 
> Makers of IGOR Pro, scientific data analysis and graphing for Mac and PC
> http://www.wavemetrics.com
> 
> 
> 
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