qt4-mac @4.7.4_0+debug+quartz fails to leave debug symbols in the resulting shared libraries

[kierans (Kieran Simpson)]

OSX 10.6.7

XCode 4.0 Build 4A304a

The compiler used was /Developer/usr/bin/llvm-g++-4.2

I noticed when debugging a segfault, even though my binary was linked to the Qt_debug libraries no line numbers or other symbols were available. My investigation found that no -g flags were passed to the Makefile.Debug LFLAGS, thus when the shared library was built the symbols disappeared.

I added the flags (-g -gdwarf-2 like what was in CXXFLAGS) and rebuilt Qt and retried my gdb session. I got symbols, line numbers, code listings, etc.

This problem was first posted to the mailing list (​http://lists.macosforge.org/pipermail/macports-users/2011-October/025840.html)

[michaelld (Michael Dickens)]

Can you provide a debug log for the build:

sudo port clean qt4-mac
sudo port -d build qt4-mac +debug > ~/Desktop/qt4-mac-build-log.txt 2>&1
bzip2 ~/Desktop/qt4-mac-build-log.txt

and then attach the compressed logfile to this ticket.

[obin.mf@…]

Cc Me!

[kierans (Kieran Simpson)]

debug log of qt4-mac +debug build

[michaelld (Michael Dickens)]

It looks from the log file like the debug libraries are being formed correctly -- with "-g -gdwarf-2". Can you double-check this ticket's issue? I did just update qt4-mac so-as to use llvm-g++ instead of clang++ -- so maybe that makes a difference? clang has some known issues already, which is why some ports cannot use it.

[kierans (Kieran Simpson)]

Upgrading to qt4-mac @4.7.4_1+debug+quartz fixed the issue.

One does have to remember to use the -k option when building the debug libraries however so that the source doesn't disappear at the end of the build.

[michaelld (Michael Dickens)]

Yes, you do need to -k(eep) the source when using dwarf2 symbols; see < ​http://doc.qt.nokia.com/stable/debug.html#debug-symbols-and-size >. IIRC, we can enable debug but disable dwarf2 so that you don't need the source any longer, but that solution takes a -lot- longer to produce, results in -much- larger libraries, and also has issues (being created at all) under 10.4 and 10.5. So, your solution is the preferred way until something better comes along.

[mkae (Marko Käning)]

Cc Me!

[macporter90210@…]

Replying to kierans777@…:

Upgrading to qt4-mac @4.7.4_1+debug+quartz fixed the issue.

One does have to remember to use the -k option when building the debug libraries however so that the source doesn't disappear at the end of the build.

I am trying to build an unrelated port for debug symbols and have similar issues. Where do you specify the -k option?

[michaelld (Michael Dickens)]

As in "sudo port -k install qt4-mac". Do "man port" for more info.