Build fails with C++20 and PoDoFo >= 0.10

[antonio-rojas]

What is the bug?

New poppler 24.05 requires C++20, but gdal fails to build with it

[ 95%] Building CXX object ogr/ogrsf_frmts/mssqlspatial/CMakeFiles/ogr_MSSQLSpatial.dir/ogrmssqlspatialdatasource.cpp.o
cd /build/gdal/src/build/ogr/ogrsf_frmts/mssqlspatial && /usr/bin/c++ -DDONT_DEPRECATE_SPRINTF -DGDAL_COMPILATION -DHAVE_AVX_AT_COMPILE_TIME -DHAVE_SSE_AT_COMPILE_TIME -DHAVE_SSSE3_AT_COMPILE_TIME -Dogr_MSSQLSpatial_EXPORTS -I/build/gdal/src/gdal-3.8.5/apps -I/build/gdal/src/gdal-3.8.5/alg -I/build/gdal/src/gdal-3.8.5/gcore -I/build/gdal/src/build/gcore -I/build/gdal/src/gdal-3.8.5/port -I/build/gdal/src/build/port -I/build/gdal/src/gdal-3.8.5/ogr -I/build/gdal/src/gdal-3.8.5/ogr/ogrsf_frmts -I/build/gdal/src/gdal-3.8.5/frmts -I/build/gdal/src/build/gcore/gdal_version_full -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions         -Wp,-D_FORTIFY_SOURCE=3 -Wformat -Werror=format-security         -fstack-clash-protection -fcf-protection         -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Wp,-D_GLIBCXX_ASSERTIONS -g -ffile-prefix-map=/build/gdal/src=/usr/src/debug/gdal -flto=auto -fvisibility=hidden -std=gnu++20 -flto=auto -fno-fat-lto-objects -fPIC -Wall -Wextra -Winit-self -Wunused-parameter -Wmissing-declarations -Wlogical-op -Wshadow -Wmissing-include-dirs -Wformat -Werror=format-security -Wno-format-nonliteral -Werror=vla -Wno-clobbered -Wdate-time -Wnull-dereference -Wextra-semi -Wfloat-conversion -Wnon-virtual-dtor -Woverloaded-virtual -Wsuggest-override -fno-operator-names -Wzero-as-null-pointer-constant -MD -MT ogr/ogrsf_frmts/mssqlspatial/CMakeFiles/ogr_MSSQLSpatial.dir/ogrmssqlspatialdatasource.cpp.o -MF CMakeFiles/ogr_MSSQLSpatial.dir/ogrmssqlspatialdatasource.cpp.o.d -o CMakeFiles/ogr_MSSQLSpatial.dir/ogrmssqlspatialdatasource.cpp.o -c /build/gdal/src/gdal-3.8.5/ogr/ogrsf_frmts/mssqlspatial/ogrmssqlspatialdatasource.cpp
In file included from /usr/include/c++/14.1.1/chrono:45,
                 from /usr/include/podofo/main/PdfDate.h:10,
                 from /usr/include/podofo/podofo.h:41,
                 from /build/gdal/src/gdal-3.8.5/frmts/pdf/pdfsdk_headers.h:120,
                 from /build/gdal/src/gdal-3.8.5/frmts/pdf/gdal_pdf.h:55,
                 from /build/gdal/src/gdal-3.8.5/frmts/pdf/pdfcreatefromcomposition.cpp:30:
/usr/include/c++/14.1.1/sstream:457:7: error: ‘struct std::__cxx11::basic_stringbuf<_CharT, _Traits, _Alloc>::__xfer_bufptrs’ redeclared with different access
  457 |       struct __xfer_bufptrs
      |       ^~~~~~

Steps to reproduce the issue

Build gdal with -DCMAKE_CXX_STANDARD=20

Versions and provenance

Arch Linux x86_64
gdal 3.8.5
gcc 13.1 and 14.1
podofo 0.10.3
poppler 24.05 (irrelevant, also happens with older poppler)

Additional context

No response

[rouault]

This has been fixed in upcoming 3.9.0 per 60dcddb . You may cherry-pick it

[antonio-rojas]

Thanks, but it's quite the opposite: the commit you linked is causing the issue, which is that gdal fails to compile with C++20 (I'm not reporting that it doesn't compile with poppler 24.05). This is still an issue in current git.

[rouault]

it's quite the opposite: the commit you linked is causing the issue,

well, not really :-) Forcing C++20 is required with Poppler >= 24.05 . But forcing C++20 also broke PoDoFo build and caused other issues (for 3.9.0). The PoDoFo issue is fixed by first commit of #9878
But if you build with Poppler, there is no point in building against PoDoFo, so it might be more robust to just disable PoDoFo support as it is rather clunky. PoDoFo builds are only useful if neither Poppler nor Pdfium are available