[Bug gdb/30368] New: GDB Python Failing to Import Zlib Module

[Bug gdb/30368] New: GDB Python Failing to Import Zlib Module

[justinpopo6 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30368

            Bug ID: 30368
           Summary: GDB Python Failing to Import Zlib Module
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: justinpopo6 at gmail dot com
  Target Milestone: ---

When compiling GDB for a non-native target, in my case x86_64 host and aarch64
target, it fails to import zlib when python library is statically linked.

(gdb) python
>import zlib
>print("hello world")
>end
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError:
/local/users/jc957059/gcc123/build/opt/toolchains/python-runtime/lib/python3.10/lib-dynload/zlib.cpython-310-x86_64-linux-gnu.so:
undefined symbol: PyExc_MemoryError
Error while executing Python code.
(gdb) exit

The python library is being statically linked to gdb, but the symbols are not
being exported. Thus the PyExc_MemoryError symbol is missing when trying to
import zlib.

Looking at this in gdb/configure:21954
# Work around Python http://bugs.python.org/issue10112.  See also
# http://bugs.python.org/issue11410, otherwise -Wl,--dynamic-list has
# no effect.  Note that the only test after this that uses Python is
# the -rdynamic/-Wl,--dynamic-list test, and we do want that one to be
# run without -export-dynamic too.
PYTHON_LIBS=`echo $PYTHON_LIBS | sed -e 's/-Xlinker -export-dynamic//'`

We remove -export-dynamic and expect to add -rdynamic/--dynamic-list. However
this is only added for native builds using configure.nat.
gdb/configure:29677
# Import nat definitions.
nat_makefile_frag=/dev/null
if test "${gdb_native}" = "yes"; then
  . ${srcdir}/configure.nat
  nativefile=$NAT_FILE
fi

gdb/configure.nat:54
case ${gdb_host} in
    *linux*)
...
       LOADLIBES='-ldl $(RDYNAMIC)'

I don't see this error for native builds since the -rdynamic flag is present
during linking, but for non-native builds this fails. Shouldn't we be adding
the -rdynamic flag for all builds? Manually setting LDFLAGS="-rdynamic" fixes
this problem for me.

uname -a:
Linux stbirv-lnx-1 5.15.0-46-generic #49-Ubuntu SMP Thu Aug 4 18:03:25 UTC 2022
x86_64 x86_64 x86_64 GNU/Linux

gcc -v:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
11.3.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-11-xKiWfi/gcc-11-11.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-xKiWfi/gcc-11-11.3.0/debian/tmp-gcn/usr
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.3.0 (Ubuntu 11.3.0-1ubuntu1~22.04)

Thanks,
Justin

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[Bug gdb/30368] GDB Python Failing to Import Zlib Module

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30368

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-08-28
                 CC|                            |tromey at sourceware dot org
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
Internally at AdaCore, we build gdb against a static libpython.
Our build setup seems to add -export-dynamic to LDFLAGS
to make this work.
I think a clean patch to do this in gdb somewhere would
be totally fine.

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