Not compile with new libxml 2.12.X

[AngryPenguinPL]

After upgrading libxml to series 2.12.X libzypp no longer compile.

 FAILED: zypp/CMakeFiles/zypp-objlib.dir/parser/xml/Reader.cc.o 
DEBUG util.py:448:  /usr/bin/c++ -DENABLE_ZCHUNK_COMPRESSION=1 -DEXPORT_EXPERIMENTAL_API -DHAVE_PIPE2 -DHAVE_RPM_VERIFY_TRANSACTION_STEP -DHAVE_UDEV -DWITH_LIBPROXY_SUPPORT -DZYPP_DLL -DZYPP_RPM_BINARY=\"/usr/libexec/zypp/zypp-rpm\" -DZYPP_WORKER_PATH=\"/usr/libexec/zypp/workers\" -D_FILE_OFFSET_BITS=64 -I/builddir/build/BUILD/libzypp-17.31.25 -I/builddir/build/BUILD/libzypp-17.31.25/build -I/usr/include/rpm -I/usr/include/libxml2 -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/builddir/build/BUILD/libzypp-17.31.25/build/zypp -I/builddir/build/BUILD/libzypp-17.31.25/build/zypp/sywu/include -I/builddir/build/BUILD/libzypp-17.31.25/libs/zypp-core -Os -fomit-frame-pointer -g3 -gdwarf-4 -Wstrict-aliasing=2 -pipe -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -fstack-protector-all --param=ssp-buffer-size=4 -m64 -mtune=generic -flto -DPROTOBUF_USE_DLLS -pthread -fno-strict-aliasing -fPIC -g -Wall -Wp,-D_GLIBCXX_ASSERTIONS -fvisibility-inlines-hidden -Woverloaded-virtual -Wnon-virtual-dtor -Werror=format-security -I/usr/include -Os -fomit-frame-pointer -g3 -gdwarf-4 -Wstrict-aliasing=2 -pipe -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -fstack-protector-all --param=ssp-buffer-size=4 -m64 -mtune=generic -flto -DPROTOBUF_USE_DLLS -std=c++17 -DZYPP_BASE_LOGGER_LOGGROUP=\"zypp\" -MD -MT zypp/CMakeFiles/zypp-objlib.dir/parser/xml/Reader.cc.o -MF zypp/CMakeFiles/zypp-objlib.dir/parser/xml/Reader.cc.o.d -o zypp/CMakeFiles/zypp-objlib.dir/parser/xml/Reader.cc.o -c /builddir/build/BUILD/libzypp-17.31.25/zypp/parser/xml/Reader.cc
DEBUG util.py:448:  /builddir/build/BUILD/libzypp-17.31.25/zypp/parser/xml/Reader.cc:119:7: error: no matching function for call to 'xmlTextReaderSetStructuredErrorHandler'
DEBUG util.py:448:    119 |       xmlTextReaderSetStructuredErrorHandler( _reader, structuredErrorFunc, NULL );
DEBUG util.py:448:        |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DEBUG util.py:448:  /usr/include/libxml2/libxml/xmlreader.h:419:6: note: candidate function not viable: no known conversion from 'void (void *, xmlErrorPtr)' (aka 'void (void *, _xmlError *)') to 'xmlStructuredErrorFunc' (aka 'void (*)(void *, const _xmlError *)') for 2nd argument
DEBUG util.py:448:    419 |             xmlTextReaderSetStructuredErrorHandler(xmlTextReaderPtr reader,
DEBUG util.py:448:        |             ^
DEBUG util.py:448:    420 |                                                    xmlStructuredErrorFunc f,
DEBUG util.py:448:        |                                                    ~~~~~~~~~~~~~~~~~~~~~~~~

Full build log: https://file-store.openmandriva.org/api/v1/file_stores/4572313c6dd54dbf32c4a91a01cbd9bd804545ed.log?show=true

Details:

• libzypp 17.31.25
• libxml 2.12.3
• Compiler Clang 17

[mlandres]

I've got no libxml 2.12. at hand, but according to the error message f80aaa4b94c9badb117308bd4032d6e2b2365627 could fix it.

[AngryPenguinPL]

Unfortunately, after applying this commit, I still have the following error:

  /builddir/build/BUILD/libzypp-17.31.25/zypp/parser/xml/Reader.cc:119:7: error: no matching function for call to 'xmlTextReaderSetStructuredErrorHandler'
DEBUG util.py:448:    119 |       xmlTextReaderSetStructuredErrorHandler( _reader, structuredErrorFunc, NULL );
DEBUG util.py:448:        |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DEBUG util.py:448:  /usr/include/libxml2/libxml/xmlreader.h:419:6: note: candidate function not viable: no known conversion from 'void (void *, const xmlErrorPtr)' (aka 'void (void *, _xmlError *const)') to 'xmlStructuredErrorFunc' (aka 'void (*)(void *, const _xmlError *)') for 2nd argument
DEBUG util.py:448:    419 |             xmlTextReaderSetStructuredErrorHandler(xmlTextReaderPtr reader,
DEBUG util.py:448:        |             ^
DEBUG util.py:448:    420 |                                                    xmlStructuredErrorFunc f,
DEBUG util.py:448:        |                                                    ~~~~~~~~~~~~~~~~~~~~~~~~
DEBUG util.py:448:  1 error generated.

[berolinux]

The fix doesn't work because const xmlErrorPtr makes it a constant pointer to a potentially non-const variable while libxml2 expects to get a pointer to a constant variable. There's probably a nicer way, but changing const xmlErrorPtr to const _xmlError * fixes it.

[mlandres]

@berolinux You're right of course. Unfortunately there's no signature which satisfies both (old and new). So your fix will not work with the old libxml.

error: invalid conversion from ‘void (*)(void*, const xmlError*)’ to ‘Told {aka void (*)(void*, xmlError*)}’ [-fpermissive]
error: invalid conversion from ‘void (*)(void*, xmlError*)’ to ‘Tnew {aka void (*)(void*, const xmlError*)}’ [-fpermissive]

We'll need an #ifdef regarding th libxml version which introduced the change.

[mlandres]

libzypp-17.31.28