[cfe-users] Should clang++ -g produce debugging info for all types?

[David Blaikie via cfe-users]

Does it work with gdb? I'm guessing maybe lldb doesn't support the build-id
feature that redhat uses (
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/developer_guide/intro.debuginfo
)
?

I'd try gdb + gcc + binutils ld (or gold) + libstdc++ (use std::fstream as
an example of something that gcc will home to the libstdc++ debug info -
dwarfdump your executable and you'll see it doesn't contain the definition
of basic_fstream, but verify the debugger can still render the full
definition). If that works, swap out various parts of that & see where it
falls apart.

On Tue, Jul 30, 2019 at 9:50 AM Bob Eastbrook <baconeater789 at gmail.com>
wrote:

> On Thu, Jul 25, 2019 at 8:35 PM David Blaikie <dblaikie at gmail.com> wrote:
>
> > No, it shouldn't - clang attempts to avoid emitting duplicate debug info
> across the program (it assumes you built the whole program and all
> libraries with debug info), gcc assumes the same thing though in slightly
> different/fewer ways.
> >
> > The solution is to install the -dbg build of your libstdc++ package
> (assuming you're using libstdc++), it will include debug info for the
> standard library, including std::string.
>
> Thanks for the pointer.  Based on what you told me, I was able to dig
> deeper and found these relevant links:
>
> https://bugs.llvm.org/show_bug.cgi?id=24202#c1
>
> https://stackoverflow.com/questions/41745527/cannot-view-stdstring-when-compiled-with-clang
>
> I installed the debug version of libstd++ on my Fedora system with
> "dnf debuginfo-install libstdc++" and I now see a debug version of
> libstdc++:
>
> $ file /usr/lib/debug/lib64/libstdc++.so.6.0.26-9.1.1-1.fc30.x86_64.debug
> /usr/lib/debug/lib64/libstdc++.so.6.0.26-9.1.1-1.fc30.x86_64.debug:
> ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux),
> dynamically linked,
> BuildID[sha1]=3b2e1aaafd0cb7e1ebd75627d4cde2504c927159, with
> debug_info, not stripped
>
> I don't have things working though.  I still don't see std::string
> info when debugging.  My executable is linked against the non-debug
> version:
>
> $ ldd a.out
>     linux-vdso.so.1 (0x00007ffec03fe000)
>     libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f2fccd31000)
>     libm.so.6 => /lib64/libm.so.6 (0x00007f2fccbeb000)
>     libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f2fccbd1000)
>     libc.so.6 => /lib64/libc.so.6 (0x00007f2fcca0b000)
>     /lib64/ld-linux-x86-64.so.2 (0x00007f2fccf45000)
>
> Is that my problem?  Or does LLDB somehow know to use the version in
> /usr/lib/debug/lib64?
>
> I'm also puzzled about why the debug version was put in /usr/lib and
> not /usr/lib64.
>
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