libcmis: fix build with gcc 16

[sgn]

Build with gcc 16 yields those errors:

atom-document.cxx: In constructor 'AtomDocument::AtomDocument(AtomPubSession*)':
atom-document.cxx:48:19: error: use of deleted function 'libcmis::Document::Document()'
   48 |     m_contentUrl( )
      |                   ^
In file included from atom-document.hxx:31,
                 from atom-document.cxx:29:
../../inc/libcmis/document.hxx:48:23: note: 'libcmis::Document::Document()' is implicitly deleted because the default definition would be ill-formed:
   48 |     class LIBCMIS_API Document : public virtual Object
      |                       ^~~~~~~~
../../inc/libcmis/document.hxx: At global scope:
../../inc/libcmis/document.hxx:48:23: error: no matching function for call to 'libcmis::Object::Object()'
  • there are 3 candidates
In file included from ../../inc/libcmis/document.hxx:39:
    • candidate 1: 'libcmis::Object::Object(const libcmis::Object&)'
      ../../inc/libcmis/object.hxx:80:13:
         80 |             Object( const Object& copy );
            |             ^~~~~~
      • candidate expects 1 argument, 0 provided
    • candidate 2: 'libcmis::Object::Object(libcmis::Session*, xmlNodePtr)'
      ../../inc/libcmis/object.hxx:79:13:
         79 |             Object( Session* session, xmlNodePtr node );
            |             ^~~~~~
      • candidate expects 2 arguments, 0 provided
    • candidate 3: 'libcmis::Object::Object(libcmis::Session*)'
      ../../inc/libcmis/object.hxx:78:13:
         78 |             Object( Session* session );
            |             ^~~~~~
      • candidate expects 1 argument, 0 provided
atom-document.cxx: In constructor 'AtomDocument::AtomDocument(AtomPubSession*)':
atom-document.cxx:48:19: note: use '-fdiagnostics-all-candidates' to display considered candidates
   48 |     m_contentUrl( )
      |                   ^
atom-document.cxx: In constructor 'AtomDocument::AtomDocument(AtomPubSession*, xmlNodePtr)':
atom-document.cxx:56:19: error: use of deleted function 'libcmis::Document::Document()'
   56 |     m_contentUrl( )
      |                   ^

[caolanm]

I think the problem is autoconf-2.72 and its interaction with the new gcc and we end up compiling with an older c++11 instead of c++14?

[sgn]

Didn't we ask for C++11 explicitly?

libcmis/configure.ac

Line 27 in e00b5b8

AX_CXX_COMPILE_STDCXX_11

checking for g++ option to enable C++11 features... -std=gnu++11                                                                                                                              
checking dependency style of g++ -std=gnu++11... gcc3   

[sgn]

I can confirm that changing AX_CXX_COMPILE_STDCXX_11 to AX_CXX_COMPILE_STDCXX_14 works.
Also, we can set CXXFLAGS=-std=gnu++14 before running ./configure also works.