Avoid unique_ptr(nullptr_t) ctor for incomplete argument type

...hoping that this will avoid

> In file included from /home/tdf/lode/jenkins/workspace/lo_ubsan/sw/source/filter/ww8/wrtw8nds.cxx:25:
> In file included from /home/tdf/lode/jenkins/workspace/lo_ubsan/sw/source/filter/ww8/docxexport.hxx:23:
> In file included from /home/tdf/lode/jenkins/workspace/lo_ubsan/sw/source/filter/ww8/wrtww8.hxx:23:
> In file included from /home/tdf/lode/jenkins/workspace/lo_ubsan/include/sot/storage.hxx:24:
> In file included from /home/tdf/lode/jenkins/workspace/lo_ubsan/include/tools/stream.hxx:28:
> In file included from /home/tdf/lode/opt_private/gcc-7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/../../../../include/c++/7.3.0/memory:80:
> /home/tdf/lode/opt_private/gcc-7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/unique_ptr.h:76:16: error: invalid application of 'sizeof' to an incomplete type 'sax_fastparser::FastAttributeList'
>         static_assert(sizeof(_Tp)>0,
>                       ^~~~~~~~~~~
> /home/tdf/lode/opt_private/gcc-7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/unique_ptr.h:268:4: note: in instantiation of member function 'std::default_delete<sax_fastparser::FastAttributeList>::operator()' requested here
>           get_deleter()(__ptr);
>           ^
> /home/tdf/lode/opt_private/gcc-7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/unique_ptr.h:233:45: note: in instantiation of member function 'std::unique_ptr<sax_fastparser::FastAttributeList, std::default_delete<sax_fastparser::FastAttributeList> >::~unique_ptr' requested here
>         constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
>                                                    ^
> /home/tdf/lode/jenkins/workspace/lo_ubsan/include/sax/fshelper.hxx:33:34: note: forward declaration of 'sax_fastparser::FastAttributeList'
> namespace sax_fastparser { class FastAttributeList; }
>                                  ^

(<https://ci.libreoffice.org/job/lo_ubsan/1767/>) with libstdc++ prior to
<https://gcc.gnu.org/git/?p=gcc.git;a=commit;
h=c3ba63c314d61362f7c48c4feeefa13ea3978344> "PR libstdc++/87704 fix
unique_ptr(nullptr_t) constructors".

Change-Id: Ie3b86b83d0b0e70fe44e2b2022d410643e265fbf
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/103139
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

0 files changed, 0 insertions, 0 deletions